Structure and bonding 0.0 / 5 ? ChemistryBonding & shapesASAQA Created by: amm242Created on: 11-05-18 12:08 When does ionic bonding occur? Between metals and non-metals 1 of 32 What happens to electrons in ionic bonding? They are transferred from metals to non-metals, forming positive and negative ions 2 of 32 What is ionic bonding the result of? Electrostatic attraction between oppositely charged ions 3 of 32 Why do ionic compounds have high melting points? Giant structures so lots of energy is needed to break up the lattice of ions. Strong electrostatic attraction between oppositely charged ions. 4 of 32 When can ionic compounds conduct electricity? When molten or dissolved in water because the ions are free to move 5 of 32 Why do ionic compounds shatter easily? Ions moving in a certain direction causes contact between like charges which repel 6 of 32 What is a covalent bond? A shared pair of electrons between a pair of non-metal atoms 7 of 32 Why do simple molecular compounds have low melting points? Strong covalent bonds are between the atom, but weak attraction is between molecules. 8 of 32 How are covalent substances held together? Electrostatic attraction between the nuclei and the shared electrons 9 of 32 What is a dative covalent bond? One atom provides both electrons in the shared pair 10 of 32 How do dative covalent bonds occur? Electron deficient atom accepts electron pair from atom donating lone pair 11 of 32 Why are covalent substance poor conductors of electricity? Molecules are neutral overall - no charged particles to carry current 12 of 32 What is metallic bonding? Giant structure - Lattice of positive ions in sea of delocalised outer electrons 13 of 32 Why does the number of delocalised electrons vary between metals/ Depends on how many electrons can be lost by each metal atom 14 of 32 Why are metals good conductors of electricity? Delocalised electrons free to move through the structure 15 of 32 Why are metals good conductors of heat? Energy spread by vigorous vibrations of closely packed ions 16 of 32 How does the charge on the ion affect strength of metallic bonding? Greater charge, greater number of delocalised electrons, stronger electrostatic attraction between ion and electron 17 of 32 How does the size of the ion affect strength of metallic bond? Smaller ion, electrons closer to positive nucleus, stronger bond. 18 of 32 Why are metals malleable/ductile? Layers of positive ions can shift positions due to delocalised electrons 19 of 32 Why do metals have high melting points? Giant structure and strong attraction between +ve ions and electrons 20 of 32 Define electronegativity The power of an atom to attract the electron density in a covalent bond to itself 21 of 32 How is electronegativity measured? Pauling scale - higher no. = more electronegative 22 of 32 What does electronegativity depend on? Nuclear charge, sheilding, distance of electrons from nucleus 23 of 32 Where are the most electronegative elements found? Top right hand corner of periodic table 24 of 32 What is polarity? Unequal sharing of electrons between atoms in covalent bond 25 of 32 When do dipole-dipole forces occur? Between molecules that have permanent dipoles - polar overall 26 of 32 What are van der Waals forces? Force of attraction between all molecules/atoms caused by instantaneous dipoles 27 of 32 When does hydrogen bonding occur? Between hydrogen and very electronegative atoms with lone pairs (NOF) 28 of 32 What happens to hydrogen atoms in hydrogen bonding? Become electron deficient 29 of 32 How is ice less dense than water? Molecules held in fixed positions which are slightly less close 30 of 32 Describe diamond Carbon atoms form four covalent bonds, giant structure, strong covalent bonds 31 of 32 Describe graphite Carbons atoms form three covalent bonds, van der Waals between layers, delocalised electrons between layers 32 of 32
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