Unit 13 worksheet chemical bonding and structure PDF

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Unit 13 worksheet chemical bonding and structure- Distinction received...

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Chemical Bonding & Structure Assignment Questions SECTION ONE a) This element has 17 electrons in total for an atomic number of 17. There are 5 valence electrons in the 3p suborbital, from this we can work out that the element will be in period 3, and the 5th element from the left in the p-block. This element is Chlorine (which has the atomic number 17). b) This element has 11 electrons, with its 1 valence electron in the 3s sub-orbital. Therefore, we know the element will be in the first element from the left in the s-block and on the 3rd period. This element is Sodium (which has the atomic number 11). c) This element has 16 electrons, with its 4 valence electrons in the 3p subshell. So, the element will be placed again on the 3rd period, 4 along from the left-hand side of the p-block which is Sulfur (which has the atomic number 16). SECTION TWO a) Calcium chloride (CaCl2) – 1 calcium atom, which has 20 valence electrons and 2 valence electrons. 2 chlorine atoms, with 17 electrons, 7 valence.

Methane (CH4) – 1 carbon atom with 6 electrons, 4 hydrogen atoms with 1 electron, 1 valence.

Nitric acid (HNO3) – 1 hydrogen atom with 1 electron, 1 valence. 1 nitrogen atom with 7 electrons, 5 valence. 3 oxygen atoms with 8 electrons, 6 valence.

b) magnesium + oxygen  magnesium oxide. Magnesium is placed on the left-hand side of the periodic table in the metals and oxygen is on the far-right hand side in the non-metal section. When metals and non-metals bond it is ionic, so magnesium oxide has an ionic bond. Calcium + chlorine  calcium chloride. Calcium is in the metal area and chlorine is in the non-metal area of the periodic table, so they would have an ionic bond. c) In carbon dioxide (CO2) both the carbon and oxygen are on the right-hand side in the nonmetal section of the periodic table, therefore we can predict that carbon dioxide will be covalently bonded as a bond between non-metal atoms generally indicates. d) You can identify the type of bonding present in a compound through looking at if the atoms are metal, non-metal or metalloids. A bond between metal atoms will be ionic, a bond between 2 non-metals will be covalent and a bond between 2 metals will be metallic. If the compound is made of atoms of the same element, it will be a non polar covalent bond, a polar covalent bond will be from 2 non-metals of different elements, or hydrogen and a non-metal. Another method is to look at the difference in electronegativity between the atoms, if the difference is between 0.0 and 0.3, the bond will be non-polar covalent, if it is between 0.4 and 1.7 it has a polar covalent bond and if it is above 1.7 it is an ionic bond. SECTION THREE a) Ionic lattices are tightly packed, ordered positive and negative ions forming larger 3D crystalline lattices. They have high melting and boiling points, are brittle, solid at room temperature, sometimes soluble in water, and do not conduct electricity. Discrete molecules have weak intermolecular forces, low melting and boiling points, do not conduct electricity and can be either gas or liquid at room temperature. Giant molecules contain lots of covalently bonded atoms and are solids at room temperature, very strong, have high melting and boiling points, and variable electrical conductivity. Metals are lattice of ions in lots of delocalised electrons, they are solid at room temperature, have high melting and boiling points, high density, and are generally good conductors of electricity. b) Ionic lattices are generally brittle due to very strong bonds between the positive and negative ions within the lattice as the opposite charges strongly attract one another. Applying pressure to the ionic lattice will displace the alignment of the ion and this will cause the ions of the same charge to get closer to each other and align. This creates electrostatic repulsion as these ions with similar charge repel each other splitting or completely disorientating the lattice infrastructure. c) Diamond and graphite are both giant molecules made entirely of carbon atoms, however they have different physical properties. They both have very high melting and boiling points and cannot be dissolved. These similarities are due to the strength of the carbon-carbon bonds. The differences are; graphite is very soft and conducts electricity, diamond is very hard, and doesn't conduct electricity. In graphite, each carbon atom bonds with 3 other atoms, in diamond each carbon bonds with 4 other atoms. Carbon has 4 valence electrons so needs 4 extra from the covalent bonds, this is achieved in diamonds and there are no delocalised electrons, so, electricity cannot be conducted. However, the carbon atoms in

graphite do not achieve this, instead, it has free electrons, allowing electricity to be conducted. The difference in toughness is because diamond has a 3D lattice which is very strong and all bonded together and graphite has layers, therefore the layers can slip apart. SECTION FOUR a) The amide ion (NH2-) has 2 lone pairs of electrons on the nitrogen atom, which repel the nucleus of the 2 hydrogen atoms. 2 lone pairs means a bond angle of 104.5, plus there are 4 pairs of shared electrons, indicating it will have a tetrahedral structure b) Electron pair repulsion theory theorises that electron pairs repel each other and assumes that atoms in molecules will have a geometry that minimises repulsion between valence electrons. Lone pairs of electrons are more repulsive than bonding pairs, as they are more electronegative or electron dense. Because these electrons want to be as far away from each other as possible, the more lone pairs there are the more the bonding pairs are repelled away towards each other. SECTION FIVE a) A homologous series is a group of generally organic chemical compounds which have the same general formula and similar chemical properties usually listed in order of increasing size. They differ by CH2 in their formula in their listed order. For example, in normal alkanes, the lower members are gases but as the chain length increases, they become liquids, and then waxy solids. The melting and boiling points increase as well. Homologous series of organic compound include alkanes, 1 alkanols, and alkanoic acids. Homologous series of inorganic compounds include phosphoric acids, silicic acids and the phosphonitrilic chlorides. b) In a homologous series a gradation in physical properties is seen. Melting and boiling points increase as you so down the series, this is due to the increase of molecular mass down the series. Solubility in particular solvents also have a gradation, but this is dependent on the type of intermolecular force between the solute and solvent. The solubility of the homologous series of linear n-alkanols in water the water solubility decreases as you go down the series due to water being a polar solvent. With this same homologous series solubility increases down the series if the solvent is nonpolar, like hexane. c) Displayed formula has most detailed structure of all the formulas, it shows the atoms of the molecule in the order they were bonded, the number and type of bonds between them. Conveyed by lines, single, double and triple bonds are shown by single double and triple dashes respectively. Structural formula are similar to displayed as it shows the order of the atoms, however it is written in a single line and not all of the bonds are shown. Carbon and hydrogen bonds are often simplified and all the atoms attached to a particular carbon atoms are shown immediately after it. The most simplified formula is the skeletal formula, which has removed the hydrogen atoms from the alkyl chains, leaving just the carbon skeleton and associated functional groups. C-C bonds are represented as a line, whilst the carbon atoms are represented by ends or bends. The hydrogen atoms are assumed as they make up the 4 carbon bonds.

d) e) When 2 or more organic compounds have the same molecular formula but different structure it is called a structural isomer. They are made up of the same atoms and the same number of atoms, but the atoms are arranged differently in space, with different bonds to other atoms and a completely difference order. This means they can have difference physical and chemical properties. If the compound is the same when it is rotated it is not a structural isomer. An example of a structural isomer is 2-methylpentane and 3-methylpentane. They are both made up of C6H14 but arranged differently due to their placement in the methyl group. References Compound Interest, 2014. A Brief Guide to Types of organic Chemistry Formulae. [online]. Available at: https://www.compoundchem.com/2014/04/11/a-brief-guide-to-types-oforganic-chemistry-formula/ [Accessed 3 June 2021]. Rsc.org, n.d. Periodic Table. [online]. Available at: https://www.rsc.org/periodic-table [Accessed 3 June 2021]. Sundas, D, n,d. What are the differences in structures of diamond and graphite? And how do they relate to their chemical properties and uses? [online]. Available at: https://www.mytutor.co.uk/answers/12203/GCSE/Chemistry/What-are-the-differences-instructures-of-diamond-and-graphite-And-how-do-they-relate-to-their-chemical-propertiesand-uses/ [Accessed 3 June 2021]. Anon, 2007. How can graphite and diamond be so different if they are both composed of pure carbon. [online]. Available at: https://www.scientificamerican.com/article/how-cangraphite-and-diam/ [Accessed 3 June 2021].

Haas, K., 2021. Valence Shell Electron-Pair Repulsion. [online]. Available at: https://chem.libretexts.org/Bookshelves/Inorganic_Chemistry/Map %3A_Inorganic_Chemistry_(Miessler_Fischer_Tarr)/03%3A_Simple_Bonding_Theory/3.02% 3A_Valence_Shell_Electron-Pair_Repulsion [Accessed 3 June 2021]. Helmenstine, A., 2019. Valence Shell Electron Pair Repulsion Theory. [online]. Available at: https://www.thoughtco.com/valence-shell-electron-pair-repulsion-theory-605773 [Accessed 3 June 2021]. The Editors of Encyclopedia Britannica, 1998. Homologous series. [online]. Available at: https://www.britannica.com/science/homologous-series [Accessed 3 June 2021]. BD Editors, 2019. Chemical Formula Definition. [online]. Available at: https://biologydictionary.net/chemical-formula/ [Accessed 3 June 2021]. Lumenlearning.com, 2017. Chemical Formulas. [online]. Available at: https://courses.lumenlearning.com/boundless-chemistry/chapter/chemical-formulas/ [Accessed 3 June 2021]. Helmenstine, A., 2019. What is Chemical Formula. [online]. Available at: https://www.thoughtco.com/definition-of-chemical-formula-604906 [Accessed 3 June 2021]....