Topic 2: Bonding Flashcards

Question

What shape and angle does a molecule with 5 bonding pairs and 1 lone pair have

Answer 1

Square Pyramidal 90 + 81.9

Answer 2

Square Planar 90

Answer 3

The ability of an atom to attracts the bonding pair of electrons from a covalent bond.

Answer 4

A small to 0 difference in En values means the compound is covalently bonded. A larger difference in En values shows some ionic character.

Answer 5

Increases Nuclear charge increases Shielding remains relatively constant across the period as no new shells are being added Nucleus attracts outer electrons This results in smaller atomic radii Therefore greater electronegativity

Answer 6

Decreases More shells are added Atomic radius increases

Answer 7

When two atoms in a bond have the same electronegativities e.g. Cl2

Answer 8

A difference of more than 1.7

Answer 9

A difference between 0.3 - 1.7

Answer 10

Some molecules have polar bonds but are overall not polar because the polar bonds in the molecule are arranged in such way that the individual dipole moments cancel each other out e.g. CCl4 or CO2

Answer 11

Forces within a molecule e.g. covalent bonds

Answer 12

Forces between molecules e.g. Hydrogen bonds, London forces, Permanent dipoles

Answer 13

Fluctuations in the electron cloud causes one side of a bond to have more or less electrons. This causes a temporary dipole to arise The temporary dipole induces a dipole on neighbouring molecules The δ+ end of one dipole is attracted to the δ- end of the next dipole, forming a London force between them

Answer 14

Forces between two molecules that have permanent dipoles are called permanent dipole - dipole forces The Forces between two molecules that have permanent dipoles are called permanent dipole - dipole forces The δ+ end of the dipole in one molecule and the δ- end of the dipole in a neighbouring molecule are attracted towards each other

Answer 15

Hydrogen bonding is a type of permanent dipole – permanent dipole bonding When hydrogen is covalently bonded to an O, N or F (very electronegative) the bond becomes highly polarised The H becomes so δ+ charged that it can form a bond with the lone pair of an O, N or F atom in another molecule e.g. Water

Answer 16

Small molecules with the same number of electrons, permanent dipole interactions are stronger than induced dipoles

Answer 17

Both are very high. Strong intermolecular forces of hydrogen bonding between the molecules in both ice (solid H2O) and water (liquid H2O) A lot of energy is therefore required to separate the water molecules and melt or boil them

Answer 18

Surface tension is the ability of a liquid surface to resist any external forces (i.e. to stay unaffected by forces acting on the surface) The water molecules at the surface of liquid are bonded to other water molecules through hydrogen bonds These molecules pull downwards the surface molecules causing the surface of them to become compressed and more tightly together at the surface This increases water’s surface tension

Answer 19

The water molecules are packed into an open lattice in water. This way of packing the molecules and the relatively long bond lengths of the hydrogen bonds means that the water molecules are slightly further apart than in the liquid form

Answer 20

As the length increases, the boiling point increases. This is because there are more London forces between molecules with longer chains.

Answer 21

Boiling point decreases as branching increases. Branching prevents molecules from being close to each other and reduces the strength of London forces

Answer 22

HF: Highest boiling point as it has hydrogen bonds which are the strongest type of intermolecular force. HCl - HBr - HI: Increases slightly from HCl. This is because there is an increase in electron number, so the strength of London forces between molecules increases.

Answer 23

Strong electrostatic force of attraction between positively charged metal ions and delocalised electrons

Answer 24

Compounds with hydrogen bonding can form hydrogen bonds with water. e.g. Alcohols When hydrogen bonds are formed between alcohols and water, enough energy is released to break H bonds between water molecules and between alcohol molecules

Answer 25

They cannot form hydrogen bonds with water, so do not release energy to disrupt the bonding between H2O molecules, so do not dissolve

Topic 2: Bonding Flashcards

Ionic, Covalent, Metallic, shapes of molecules, properties of water