Chemical bonding

Question 1

Ionic bonding

Answer 1

Electrostatic attraction between positive and negative ions in an ionic crystal lattice
Metals lose electrons
Non-metal gain electrons
Indicated by dot and cross diagrams

Question 2

Covalent bonding

Answer 2

The sharing of one or more pairs of electrons between two non-metal atoms
Indicated by dot and cross diagrams

Question 3

Coordinate/dative bonding

Answer 3

When one atom provides both the electrons needed for a covalent bond
Needs one atom having a lone pair of electrons and a second atom ha ing an unfilled orbital to accept the lone pair

Question 4

Electron-pair repulsion theory

Answer 4

A pair of electrons will repel one another to be as far apart as possible from each other (until the repulsive forces are minimised)
Leads to the shape and bond angles of covalent molecules
Order of repulsion is lone pair-lone pair>lone pair-bond pair>bond pair-bond pair

Question 5

Trigonal planar

Answer 5

Eg. BF3
3 bond pairs
No lone pairs
3 pairs of electrons repel equally
Bond angles of 120

Question 6

Linear

Answer 6

Eg. CO2
2 bond pairs
No lone pairs
2 pairs of electrons will repel equally
Bond angles of 180

Question 7

Tetrahedral

Answer 7

Eg. CH4
4 bond pairs
No lone pairs
4 pairs of electrons repel equally
Bond angles of 109.5

Question 8

Pyramidal

Answer 8

Eg. NH3
3 bond pairs
1 lone pair 
1 lone pair has more repulsion so pushes bonds closer together
Bond angles of 107

Question 9

Non-linear

Answer 9

Eg. H2O
2 bond pairs
2 lone pairs
2 lone pairs have more repulsion so push bonds closer together 
Bond angles of 104.5

Question 10

Octahedral

Answer 10

Eg. SF6
6 bond pairs
No lone pairs
6 pairs of electrons repel equally 
Bond angles of 90

Question 11

Trigonal bipyramidal

Answer 11

Eg. PF5
5 bond pairs 
No lone pairs
5 pairs of electrons repel equally 
Bond angles of 90 and 120

Question 12

Hydrogen bonding

Answer 12

Strongest type of intermolecular force

Between a hydrogen atom covalently bonded to an F, O or N atom with and available pair of electrons

Question 13

Electronegativity

Answer 13

Ability of an atom which is covalent bonded to another atom to attract the bond pair of electrons toward itself

Question 14

Bond length

Answer 14

Distance between the two nuclei of the bonding atoms

Multiple bonds are shorter than single bonds

Question 15

Bond polarity

Answer 15

Unequal sharing of electrons between two atoms forming a covalent bond with different electronegativity values (polar bond)
Non polar bond is when the electronegativity values of two atoms that form a covalent bond are the same

Question 16

Forces between molecules are called

Answer 16

Intermolecular forces

Question 17

Van der Waals forces exist

Answer 17

Between all atoms or molecules and are very weak

Question 18

Instantaneous or temporary dipoles

Answer 18

Occur in non-polar molecules
Electron charge clouds are constantly morning and so sometimes more if the charge cloud is on one side of the molecule than the other which means one end of the molecules has, for a short moment, a more negative charge than the other end
This dipole can induce a dipole on neighbouring molecules

Question 19

Permanent dipoles occur in

Answer 19

Polar molecules

And between molecules containing polar bonds

Question 20

Metallic bonding

Answer 20

Attraction between positive metal ions and delocalised electrons with the ions packed closely together in a lattice
Strong bonding

Question 21

Ionic bonding physical properties

Answer 21

High melting and boiling points because of strong electrostatic forced between ions
No electrical conductivity when solid as ions unable to move
Brittle
Often soluble in water

Question 22

Covalent bonding physical properties

Answer 22

Low melting and boiling points as only Van der Waals
No electrical conductivity
Usually insoluble in water

Question 23

Metallic bonding physical properties

Answer 23

High melting and boiling points because of strong electrostatic forces
Conduct electricity
Malleable and ductile