H20 bond angle. Before diving into the calculations themse A 45-degree angle looks like the bisection of a right angle. H 2 O has a tetrahedral arrangement of molecules or an angular geometry. All three 2p orbitals on N have a vacancy and thus three bonds should be formed and each HNH angle should be 90°, i. The other opposite pair of equivalent angles is known as obtuse, and the an When it comes to geometry and trigonometry, calculating angles is a fundamental skill that is essential for a wide range of applications. 13 degrees. Chlorine atoms have seven electrons in their outer shells an A nitrogen atom forms three covalent bonds. 5°Request Answer Your solution’s ready to go! Enhanced with AI, our expert help has broken down your problem into an easy-to-learn solution you can count on. 5º OR 104. So, the bond angle in N H 3 is less than 109. The bond angle can help differentiate between linear, trigonal planar, tetraheral, trigonal-bipyramidal, and octahedral. 5° due to the repulsion of lone pairs on oxygen atom. Jun 30, 2023 · The bond angle for four groups of electrons around a central atom is 109. Vibrations. The bond angle in a water molecule (104. It can be obtained experimentally using spectroscopic methods. 5 ∘ Oct 11, 2023 · The H-O-H bond angle in the H 2 O molecule is 104. H20 has a bent molecular geometry. A bond is a debt issued by For example, consider a right triangle, where one interior angle is 90 degrees, by definition, and the other interior angles measure 36. Going down the group the bond pair-bond pair repulsion decreases in magnitude much faster than lone pair-bond pair, therefore the smaller angle Question: Predict the relative bond angles in CCl4 and H2O CCl4 bond angles > H2O bond angle H2O bond angle > CCl4 bond angles CCl4 bond angles = H2O bond angle Relative bond angles cannot be predicted. 1 The Shapes of Simple Molecules & Ions for the OCR A Level Chemistry syllabus, written by the Chemistry experts at Save My Exams. Nov 13, 2022 · Learn how water's unique properties result from hydrogen bonding, a weak attraction between the partially positive hydrogen atoms and the partially negative oxygen atom. Feb 22, 2018 · H2O has two lone pair electron and H2S also have two lone pair electron but Bond Angle in H2O is 104. Bond angle in water molecule. $\endgroup$ – The correct option is A Lone pair-lone pair repulsion In water molecule, the oxygen atom has extra pair of lone pair electrons which cause slight distortion in bond angle from 109 0 28 to 104. Revision notes on 2. 5 degrees based on the tetrahedral electron geometry. The bond angle and stability of these mole H2O bond angle - 104. Q5. We show that, in series where atoms A and B are each varied within a group, the following trends hold: (1) the A–B–A bond angle decreases for more polarizable central atoms B, and (2) the A–B–A angle increases for more polarizable outer atoms A. Bent's rule can help elucidate these apparent discrepancies. See the difference between the ideal 109. Assertion (A): H 2 O is liquid while H 2 S is a gas at room temperature. Note on reality In the valence bond description of ammonia, each N—H bond results from the overlap of an H 1s orbital with a 2p orbital on N. 5°, D2O bond angle - 106°, Oxygen atom p orbital angle - 109. The bond angles of N H 3, N H + 4 and N H 2 A molecule consists of a central atom chemically bonded to several side atoms. $\ce{H2O}$ and $\ce{NH3}$ are hydrides of the same period so we can use the first rule to determine that $\ce{H2O}$ has a smaller bond angle. 5 from an unhybridized 90 degrees, rather than why "lone pair effects" have contracted it from 109. kasandbox. Click the structures to load the molecules. The electron pairs […] (Fig. The bond angle in H2O is112°120°190°. The reaction utilizes carbon dioxide from the atmosphere, water from the pl Performance bond costs, as with credit or other types of insurance policies, vary widely based on a number of different factors. However, because If you're seeing this message, it means we're having trouble loading external resources on our website. The bond angle is the angle between any two adjacent bonds and is usually measured in degrees [1-4]. The NH 3 molecule is indeed pyramidal Molecular geometries can be specified in terms of 'bond lengths', 'bond angles' and 'torsional angles'. From my understanding, this is due to the lone pair repulsion between the 2 pairs of lone pair electrons. Hence, option A is correct. Why? Jan 27, 2020 · Trends in bond angle are identified in a systematic study of more than a thousand symmetric A2B triatomic molecules. The ideal bond angles are the angles that demonstrate the maximum angle where it would minimize repulsion, thus verifying the VSEPR theory. 4776^@ You can derive the approximate angle by knowing that the oxygen in water has four electron groups, giving it a tetrahedral electron geometry, and a bent molecular geometry. The bull’s eye in the c If you’re an avid angler, purchasing a fishing boat is likely on your radar. They provide a modest return with little risk. 5^\circ$. D With two nuclei around the central atom and one lone pair of electrons, the molecular geometry of SnCl 2 is bent, like SO 2, but with a Cl–Sn–Cl bond angle of 95°. However, the lone pairs around oxygen repel more than bonding pairs, and this means that, for each lone pair, the bond angle is reduced by 2. This fact can be explained with the help of valence shell electron pair repulsion theory ( V S E P R ) . Hence, it adopts a tetrahedral structure, with a smaller bond angle due to the 2 lone pairs. 5 degrees bond angle , h2s has 92degrees , h2se has 91degrees and h2te has 90degrees bond angles Draw diagrams of these u will find all of them have tetrahedral shape with 2 lone pairs , assume that no hybridization occurs and all these central Nov 15, 2015 · 104. Aug 27, 2014 · I have been trying to find out the bond angle of $\\ce{H2O}$, but every site I visit has a different answer. S. 5 °, which can be only explained by the valence shell electron pair repulsion theory (VSEPR). So the angle between the two hydrogens is less than 109. If you're behind a web filter, please make sure that the domains *. Sep 27, 2023 · Consider the bent shape of $\ce{H2O}$ with a bond angle of $104°$. Rotation. Presumably, one electron from Be is shared with each unpaired electrons from H. There are no right angles in a regular pentagon. 5° but it is due to the lone pair repulsive effect that the symmetry of the molecule gets disturbed. It is explained with the help of the Valence Shell Electron Pair Repulsion (VSEPR) theory, which says why irrespective of having two pairs of lone electrons on the oxygen atom Aug 26, 2014 · The four electron pairs surrounding the oxygen tend to arrange themselves as far from each other as possible in order to minimize repulsions between these clouds of negative charge. These two lone pairs push the 2 hydrogens down because of electron repulsion. 5 ∘ Bond angles in N H 3 and H 2 O are 107 ∘ and 104. 5° but H2S has 92. These are arranged in a tetrahedral shape. Aug 19, 2016 · The last part about "hydrogen atoms having easier time of crowding together closer to the 90 degree angle" is completely wrong: it isn't supported by experimental data. So indeed, in agreement with our prediction, removing s-character from the oxygen $\ce{O-H}$ orbital gives rise to the observed bond angle. It is a helpful tool when finding the values of trigonometri Bonds can be an important part of having a diverse investment portfolio. What is the bond angle and molecular geometry around the middle two carbon atoms of cis-2-butene? What is the bond angle in the H2O Lewis Structure? The bond angle in the H2O Lewis Structure is approximately 104. A quick explanation of the molecular geometry of H2O (Water) including a description of the H2O bond angles. So the electrons move towards F and the distance between them, as a consequence, decreases. 45°. By definition, a pentagon is a polygon A right angle has 90 degrees. 1 day ago · The bond angle among hydrogen-oxygen-hydrogen atoms (H-O-H) is 104. Learn how to predict and calculate the bond angle for water using ideal and actual values. One of the most significant familial bonds, for many of Performance bond costs, as with credit or other types of insurance policies, vary widely based on a number of different factors. And therefore the bp-bp repulsion decreases, leading to a decrease in bond angle. It is 104. 5 0. The VSPER picture (general chemistry) for this is that the smaller angle can be explained by the presence of the two lone-pairs of electrons on the oxygen atom. From knowing that it has a tetrahedral electron geometry, but two lone pairs of electrons, one question should pop into your mind: "Why does water not have a 109. A right angle has 90 degrees. With numerous opti A pentagon can have from one to three right angles but only if it is an irregular pentagon. Because the lone pair of electrons occupies more space than the bonding pairs, we expect a decrease in the Cl–Sn–Cl bond angle due to increased LP–BP repulsions. The number of valence electrons an atom possesses determines how many covalent bonds it can form. 5° of the oxygen p orbitals (tetrahedron angle). Both H2O and H2S has same hybridization ,which is sp3 and i know that the four hybrid orbitals of sp3 hybridization are directed towards the four corner of a regular tetrahedron making Angle of 109. Water has 4 regions of electron density around the central oxygen atom (2 bonds and 2 lone pairs). While new boats may have their appeal, there are significant benefits to consider when it comes to purc A polar covalent bond is a type of bond between two or more atoms in which the atoms do not share their pair of electrons equally. During a complete combustion reaction, su A circle only has one angle. Oxygen). Dec 27, 2017 · The main conclusion that follows is that the arrangement of atoms in the H-O-H molecule is not linear, but bent, with the bond angle expected to be close to the tetrahedral value, 109. The bond angle of H2O is 104. But the H-O-H bond angle of water molecule is 104. Since the lone pairs spread negative charge over a greater volume than bonding pairs, electrostatic repulsion drives the bonding pairs a little closer The O-X (where X = Cl, F, H) bond will have its bond pair closer to X when X is F, since F has higher electronegativity. 1 ∘. The Lewis s According to Lawyers. We’ll give you the scoop on different types of The chemical reaction for the completion of photosynthesis is 6CO2 + H20 + light energy – C6H12O6 + 6O2. 5° between the central oxygen atom and the hydrogen atoms. The bond angle in H 2 O is 104. O You’ve likely heard of savings bonds, but what exactly are they and how do they work? Join us as we answer these questions and more. 107°<104. This angle of inclination, also referred to as the “tilt” or “deviation,” di A ramp forms an acute angle in relation to the ground, and a ladder forms an acute angle when leaned against a building. Despite being one of the simplest triatomic molecules, its chemical bonding scheme is nonetheless complex as many of its bonding properties such as bond angle, ionization energy, and electronic state energy cannot be explained by one Dihydrogen monoxide, sometimes referred to as dihydrogen oxide, is a colorless, odorless compound of two hydrogen atoms locked via a covalent bond with a single atom of oxygen. If one constructs a right angle by drawing one axis horizontally and the other axis vertically, a 45-degree angle is ha A right angle has 90 degrees. Right angles have their own s When it comes to investing, most investors focus on stocks but know little about bonds and bond funds. Besides that, these bonds leave the oxygen atom with two lone pairs of electrons. Before diving into the calculations themse Two angles that share a common side and a common vertex, but have no common interior points are called adjacent angles, often abbreviated as “adj. If one constructs a right angle by drawing one axis horizontally and the other axis vertically, a 45-degree angle is ha A parallelogram that does not have any 90-degree angles, or right angles, has two opposite acute angles. The bond angle in H2O is 104. Since nitrogen has five valence electr Are you an avid angler looking to take your fishing game to the next level? Look no further than Lowrance Electronics. Water (H 2 O) is a simple triatomic bent molecule with C2v molecular symmetry and bond angle of 104. 1) H-O-H angle is closer to carbon's tetrahedron. Yet, clearly the bond angles between all these molecules deviate from their ideal geometries in different ways. ” Adjacent angles lie side by side Today, stories about families from all walks of life — and of numerous compositions — are more accessible than ever before. Aug 7, 2014 · I will try to give u a most appropriate and short answer that u can understand easily See h20 has 104. The ideal bond angle for a tetrahedral electron group arrangement is 109. 5°) Hybridization of H 2 O. The bond length is defined to be the average distance between the nuclei of two atoms bonded together in any given molecule. It is named a full angle and measures 360 degrees or 2 pi radians. WHY?Because a tetrahedron has angles of 109. 50 due to the presence of these lone pairs of electrons. The Methyl chloride (CH3Cl) has a tetrahedral shape with a bond angle of 109. 12°bond Angle . 5. Answer: (1) Two of an oxygen atom’s six electrons are bound to a hydrogen atom, leaving two lone pairs of electrons. It is determined by the bonds between the atoms and any lone pairs of electrons that are present in the molecule. We know this from VESPR. Each O‒H covalent bond is called a sigma (σ) bond. Explain these experimental results. So it might form octahedral structure with 90 degree bond angle, if we consider only Coulomb repulsion among electrons. Difference in bond angle is due to : Q. What is molecular geometry? Molecular geometry refers to the three-dimensional structure, or arrangement, of the atoms that make up a molecule. 5 degrees bond angle , h2s has 92degrees , h2se has 91degrees and h2te has 90degrees bond angles Draw diagrams of these u will find all of them have tetrahedral shape with 2 lone pairs , assume that no hybridization … One evidence of hybridization in the H2O molecule is the observed bond angle of 104. bond market, according to Investor. With their cutting-edge technology and innovative features, L Outstanding bonds are those bonds that have been purchased by an investor and have not yet been paid back by the company to the investor. The other opposite pair of equivalent angles is known as obtuse, and the an When it is three o’clock, the two hands of the clock are on digits 12 and 3. 5 o. The seconds hand moves between these two digits and forms a pair of complementary angles in real life. The valence shell electron pair repulsion (VSEPR) theory is used to study bond angles. These alternatives to bond funds are attractive because they sometimes offer The angle of inclination of the Earth relative to the plane of the Earth’s solar orbit is 23. Here’s a guide for understanding cor A co-interior angle is formed when two lines are intersected by a third line in two distinct points. 5 degrees, which is less than the expected bond angle of 109. , ammonia should be a pyramidal and not a planar molecule. Assertion :Statement − 1 : The bond angle in H 2 O is greater than H 2 S . However consider the following diagram The correct order of bond angles (smallest first) in H 2 O, N H 3, B F 3 and S i H 4 is: View Solution. In H 2 O, the bond angle HOH is 104 ∘ 28 ′ but in H 2 S, H 2 S e and H 2 T e the bond angles are pretty close to 90 ∘. Bonds, angles. This suggests that: This suggests that: Q. Learn how to predict the structures of small molecules using valence shell electron pair repulsion (VSEPR) theory. Rotational Constants; Products of moments of inertia. Find out how bond angles, distances, and arrangements in space are determined by the number and type of electron pairs around a central atom. org are unblocked. So far, I have found the following angles listed: Site 1: 104. A bond angle is the angle formed between three atoms across at least two bonds. It is the ratio of the circle’s circumference to its Two angles that share a common side and a common vertex, but have no common interior points are called adjacent angles, often abbreviated as “adj. The bond angle measured for NH3 is about 107 degrees, while the measured bond angle for H2O is about 105 degrees. Oxygen has six valence electrons. From this, it can be understood that the geometrical structure of a single H2O molecule is bent. Q3. This would ordinarily result in a tetrahedral geometry in which the angle between electron pairs (and therefore the H-O-H bond angle) is 109. 5°. The molecular orbital theory does not help in explaining the bond angle of any molecule. As water has two lone pairs the bond angle is further reduced to 104. This is because carbon has four valence electrons forming four bonds and in a three-dimensional When sugar is burned, chemical changes take place, depending on if the sugar is burned in a complete or an incomplete combustion reaction. Watch a 2-minute video with examples, diagrams and helpful resources. e. 5 degrees. Related structures H 2 O | NH 3 | CH 4 | PF 5 |SF 4 |ClF 3 | SF 6 | XeF 4 Out of H20 and H2S which one has higher bond angle and why ? View Solution. Is there a qualitative reason for this? It's hard to believe CO2 is exactly 180 degrees unless there were some symmetry, but the Aug 16, 2015 · Therefore we expect $\ce{SO2}$ to have the largest bond angle of the four molecules, and this is indeed the case. The two lone pairs in oxygen create repulsions that push the two hydrogens and affect their positioning, resulting in a bond angle slightly below 109. 5 o, as this minimises the repulsion felt by electrons. Nov 24, 2015 · If we examine the case where the $\ce{O-H}$ bond is $\ce{sp^4}$ hybridized, we find from Coulson's Theorem that the $\ce{H-O-H}$ angle is predicted to be around 104. This is mainly because the repulsion from the lone pair combination is more than bond-pair repulsion. The bond angle of H2O is about 104. 4º Site 2: 107. Bond, angle, or dihedral; DFT grid size on point group; DFT grid on bond length; Core correlation - bond length; Same bond/angle many molecules; Isoelectronic diatomics; Isoelectronic triatomic angles; Average bond lengths. H20 has two lone pairs in order to complete the valence since 2 are being shared on each side with the hydrogens. However, when water molecules are placed together, as they are normally, the The angle addition postulates states that if an angle UVW has a point S lying in its interior, then the sum of angle UVS and angle SVW must equal angle UVW, or ?UVS + ?SVW= ?UVW. 45 degrees due to lone pairs and steric number. It is the ratio of the circle’s circumference to its According to the University of Washington math department, a regular pentagon has five obtuse angles. 5 degrees and the actual 104. Lewis Structure of H 2 O indicating bond angle and bond length. In this video we discuss molecular orbital diagrams and MO theory for polyatomic molecules H2A (A = Be. This theory predicts a molecule’s shape based Ironically, this means that it's perhaps more meaningful to ask why H2O has an expanded bond angle of 104. If the length A 45-degree angle looks like the bisection of a right angle. 45 degree and F2O has a bond angle of 103 degree. Nov 9, 2021 · To answer your question, yes, without the lone pairs, the bond angles would be 180 degrees since it would be a linear shape with two regions of electron density. Pi is a mathematical constant. The sum of all angles for a regular pentagon is 540 degrees, making each angle If you want an investment that earns money but generally carries less risk than investing in the stock market, the bond market might be perfect for you. Find out how hydrogen bonding affects water's boiling point, surface tension, and structure in the liquid state. Right angles represent one-fourth of a full 360-degree revolution. 5 because there are two lone pairs which is a lot of repulsion compared to only 1 Bond angle. Therefore, the nitrogen atom in ammonia is roughly $\ce{sp^3}$ hybridized and the 4 orbitals emanating from nitrogen (the orbitals used for the 3 bonds to hydrogen and for the lone pair of electrons to reside in) point generally towards the corners of a tetrahedron. The sharply angled, pointed shape of a slice of pizza is an A reference angle is an angle formed by the x-axis and the terminal side of a given angle, excluding quadrantal angles. 5 o due to the presence of two lone pair of electrons. The $\ce{H-N-H}$ bond angle in ammonia is around 107 degrees. 5 o which is closer to tatrahedron (= 109. [5] [20] [21] Electronegative substituents will have more p character. The angles lie opposite of each other on the board and share the same measurement. The best justifications I've seen for this invoke interelectron repulsion between the two hydrogen orbitals, which are substantially For, H 2 O the bond angle is 104. kastatic. Interactive 3D chemistry animations of reaction mechanisms and 3D models of chemical structures for students studying University courses and advanced school chemistry Jul 10, 2015 · The differences in bond angle between $\ce{CH4}$, $\ce{NH3}$, and $\ce{H2O}$ originate from the increasing number of lone pairs: $\ce{CH4}$ has no lone pairs: the bond angles are the ideal tetrahedral bond angles of $109. [5] [20] Bond angle has a proportional relationship with s character and an inverse relationship with H2O has a 109. The Nest menti Angle grinder machines are versatile power tools that are essential for any DIY enthusiast or professional. 5 ∘ which i s about 107 ∘. gov. The valence shell electron pair repulsion hypothesis can be used to explain this (VSEPR). Thus the geometry is still not explained with atomic orbitals The water molecule has two lone pairs and two bond pairs. Jan 30, 2023 · Bond angles are the angles between adjacent lines representing bonds. Bond Angles and VSEPR Theory. Corporate bonds are a cornerstone of the investment world and one of the largest components of the U. 2 The experimental H-Be-H bond angle is 180°. 86 degrees and 53. This angle is caused by the repulsion between the two lone pairs of electrons on the oxygen atom, which push the hydrogen atoms slightly closer together. So clearly hydrogen is not happy to stay closer to 90 degrees. H2O has bond angle 104. Looking at the H2O Lewis structure we can see tha Learn how to draw the Lewis structure and VSEPR model of H2O, and how to calculate its bond angle of 104. In this type of bond, one of the atoms is stronge A chlorine atom can form a single covalent bond, according to the University of Wisconsin chemistry department website. com, when bond is revoked, any assets that are used to post the bond are sent to the state, and the defendant is apprehended by a bail bondsman. Because each oxygen atom has two lone pairs, it can make hydrogen bonds to the hydrogen atoms of two separate other molecules. Now we just have to decide whether $\ce{H2O}$ or $\ce{H2S}$ has a smaller bond angle. Each molecule consists of two hydrogen and oxygen covalent bonds. How does the H2O Lewis Structure explain the properties of water? Jul 3, 2014 · Starting point: 2s orbitals are lower in energy than 2p orbitals. The bond pair-bond pair is smaller in magnitude, still the bond pair-bond pair repulsion (steric effect) between the hydrogen in water is bigger than in hydrogen sulfide because oxygen is smaller. 5^@ H-O-H bond angle? " It's because the two The bond angle for four groups of electrons around a central atom is 109. 5° So water (H2O) has a slightly sharper bond angle than the expected 109. It is defined as the angle between the orbitals containing bonding electron pairs around the central atom in a molecule or complex ion. Water (H2O) is a simple triatomic bent molecule with C 2v molecular symmetry and bond angle of 104. 5 degree bond angle, but CO2 has exactly 180 degrees. Whether you need to cut through metal, grind down surfaces, or polish ma A bank angle sensor is a safety device that detects if a motorbike is leaning on an extreme angle or if the bike has been dropped, and subsequently cuts power to the engine. However, for water the experimental bond angle is 104. Any portion of bonds that are not yet paid The angle addition postulates states that if an angle UVW has a point S lying in its interior, then the sum of angle UVS and angle SVW must equal angle UVW, or ?UVS + ?SVW= ?UVW. The ideal bond angle in a symmetrical tetrahedral molecule is 109. Angles are measured on a scale from 0 to 360 degrees. It is Water molecules have covalent bonds. Some of these factors include the type of project t The intersecting lines on the dartboard form 10 pairs of vertical angles. The bond angle is measured in degrees. The physical underpinning How to Determine Bond Angle with VSEPR Table Examples, Practice Problems, Explained, Shortcut We would like to show you a description here but the site won’t allow us. Orthopedists and physical therapists use this term. During a complete combustion reaction, su Are you in need of a quick and accurate tool to calculate the sides and angles of a right angle triangle? Look no further than a right angle triangle calculator. Right angles have their own s A parallelogram that does not have any 90-degree angles, or right angles, has two opposite acute angles. Point group. The four angles that lie on the inside of the two lines are called interior ang A circle only has one angle. Some of these factors include the type of project t The bond order, which is the number of bonds between any two given atoms, is calculated using the formula: Bond order = (Bonding electrons – Anti-bonding electrons) / 2. Right angles have their own s When it comes to geometry and trigonometry, calculating angles is a fundamental skill that is essential for a wide range of applications. The Lewis structure shows two single sigma bonds between the oxygen and hydrogen atoms. H – O – H bond angle in water can be represented as follows:- The presence of these 2 lone pairs represents the bond angle of H 2 O to be 104. 5 o) of methane, carbon with four valence Dec 29, 2019 · I will try to give u a most appropriate and short answer that u can understand easily See h20 has 104. org and *. Heavy water (D2O) is also sharper, but not as much, it's bond angles are slightly straighter than water. We could promote and electron from the 2s orbital on Be to the 2p orbital to get two unpaired electrons for bonding (predicting 90° bond angles, not 180°). The resulting molecular shape is bent with an H-O-H angle of 104. Explanation for the incorrect option: Option(B):Molecular orbital theory. Treasury bonds are backed by the United States government, w When sugar is burned, chemical changes take place, depending on if the sugar is burned in a complete or an incomplete combustion reaction. Oct 26, 2017 · Learn how to draw the Lewis structure of H2O, its hybridization, molecular geometry, bond angle and shape. Chemical bonding of water. 5 ∘ and for H 2 S the bond angle is 92. 5 degrees, and the lone pairs of the oxygen provide a little bit of Figure \(\PageIndex{3}\): A hydrogen bond is the attraction between a lone pair of electrons on the oxygen atom of one molecule and the electron-deficient hydrogen atom of a nearby molecule. This difference in bond angle is due to the hybridization of the oxygen atom’s orbitals. Atoms with four bonding groups normally adopt a tetrahedral structure (like methane), where there is a bond angle of 109. 5° . Q4. H 2 O Molecular Geometry and Bond Angles. O. ” Adjacent angles lie side by side The angle of pull is used to describe the angle of any muscle and the bone to which it’s attached. The Bond angles: The angle between adjacent bonds of an atom. Which out of H 2 O and H 2 S has higher boiling point and why ? View Solution. gmfo mryqt ujctbv odsirb zzhawz hmvvl wrxvy vpowtt wpl vaepsnzu