A31 + A32 Comparing Covalent and Ionic Bonds Between Atoms [Unit 3]

in answers... 1. blah blah blah = ionic compounds 2. blah blah blah = molecular/covalent compounds

how do covalent bonds use electrons to hold (bond) atoms together?

electrons are shared (either equally or unequally) between atoms (of molecular compounds nm+nm) so that all atoms can have their required octet of electrons (when drawing covalent bonds, use a line) (one line=two shared electrons)

how do ionic bonds use electrons to hold (bond) atoms together?

a positive metal cation forms when it donates one or more electrons to a non-metal atom creating a negatively charged anion (drawn using lewis dot diagrams with ions drawn in square brackets) (greater the charge difference, stronger the bond ex. -1 +1 < -3 +3)

what are intermolecular forces?

attractive forces between molecules (much weaker than covalent bonds) (represented by dotted lines)

types of atoms are involved in ionic and molecular/covalent compounds?

1. m+nm or m+polyatomic ion (NH4)

2. nm+nm (many nm together)

state of most compounds at room temperature?

1. solids - most are white crystals

2. some are gases, solids, or liquids

melting points?

1. very high melting point (ionic bonds are very strong)

2. lower melting points (atoms held together by weak, intermolecular forces)

boiling points?

1. very high boiling points (ionic bonds are very strong)

2. lower boiling points (atoms held together by weak, intermolecular forces)

ability to conduct electricity when melted (liquid)?

1. yes (when melted, ionic compounds have free moving ions)

2. no (when melted, molecular compounds have no free moving ions)

ability to conduct electricity when dissolved into ions in water?

1. yes (when melted, ionic compounds have free moving ions)

2. no (when melted, molecular compounds have no free moving ions)

solubility in water?

1. most are soluble in water

2. only polar substances are soluble in water

solubility in non-polar substances (like oil)

1. no, not soluble in non-polar substances

2. non-polar substances can dissolve in other non-polar substances

volatility?

1. low volatility (it does not vaporize)

2. high volatility (evaporate easily)

do they have an oder?

1. no, they do not have an oder

2. yes, they can have an oder

when they are in solid form, what holds the atoms/ions together?

1. ionic bonds in a crystal lattice structure

2. weaker, intermolecular forces

what are metallic solids?

solids that consist of only metal atoms. metal atoms held together by metallic bonds. in this special type of bond, the large group of metal atoms share electrons as a group. these are called delocalized electrons because they move around between many metal atoms and not back forth between the same to atoms like in a covalent bond. if more than one type of metal element is mixed together, it creates an alloy. metallic solids do not have an oder.

description of diamond bonds

carbons covalently bonded to 4 other carbons, extremely high melting point, strongest substance

description of graphite bonds

carbons are covalently bonded to 3 other carbons