Topic 3: Bonding

Question 1

Ionic

Answer 1

Large differences in electronegativity, between metals and non metals. Electrostatic att’n b/w charged ions.

Question 2

Covalent

Answer 2

Small differences in electronegativity, between non metals. Shared pair of electrons.

Question 3

Metallic

Answer 3

Between metals. Electrostatic att’n b/w ions and delocalised e-

Question 4

Ionic Structure

Answer 4

Giant ionic lattice

Question 5

Ionic Properties

Answer 5

• High melting point … strong att’n between oppositely charged ions means hard to overcome, higher the charge, higher the att’n, higher the melting point
• Electrical conductor when molten/ in sol’n… Ions can dissociate and so are free to move and can carry charge.

Question 6

Covalent Properties (Diamond and Sillicon)

Answer 6

• High melting point/ hard… lots of strong covalent bonds, hard to overcome.

Question 7

Covalent Properties (Graphite)

Answer 7

• High melting point (same reason as diamond)
• Slippery… weak v.d.w. between layers so can slide
• Conducts electricity… single delocalised electron can carry charge

Question 8

Covalent Properties (Iodine)

Answer 8

• Low boiling point… weak v.d.w. forced between molecules, little energy required to overcome.

Question 9

Metalic Properties

Answer 9

• High melting point… strong att’n between delocalised electrons and cations, greater the charge the more electrons, the stronger the att’n.
• Electrical conductors… delocalised electrons can move throughout structure and carry charge
• Malleable/ ductile… layers of ions can slide also means brittle

Question 10

Malleable def

Answer 10

The ability of a something to be deformed or shaped without breaking

Question 11

Ductile

Answer 11

The ability of a something to be stretched or drawn into wire form without breaking

Question 12

Dative Bonding

Answer 12

A covalent bond in which both electrons come from the same atom (a lone pair).

Question 13

2 Bonding pairs

Answer 13

Linear, 180°, O=C=O

Question 14

3 Bonding pairs

Answer 14

Trigonal Planar, 120 °, looks like flat triangle with 3 bonds, BF3

Question 15

4 Bonding pairs

Answer 15

Tetrahedral, 109.5 ° 3D shape you know it, CH4

Question 16

5 Bonding pairs

Answer 16

Trigonal Bipyramid, 120° and 90° straight up, straight down, straight left, right up to the back, right down to the front, PCl5

Question 17

6 Bonding pairs

Answer 17

Octahedral, 90°, straight up, straight down, sides up, sides down, SF6

Question 18

3 Bonding pairs, 1 Lone pair

Answer 18

Trigonal Pyramid, 107°, tetrahedral without the top atom, NH3

Question 19

2 Bonding pairs, 2 Lone pairs

Answer 19

Angular, 104.5°, V shapes, H20

Question 20

Intermolecular Forces

Answer 20

The attractive and repulsive forces that arise between the molecules of a substance.

Question 21

Van der Waals forces

Answer 21

• Weakest IMF
• Exist in all molecules or atoms
• The electron charge cloud constantly moving (electron density is uneven)
• The electron charge cloud can be more on one side of the atom or molecule than the other
• This causes a temporary dipole to arise
• This induce a dipole on neighbouring molecules
• When this happens, 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
• Because the electron clouds are moving constantly, the dipoles are only temporary

Question 22

Strength of V.d.w difference in different molecules

Answer 22

The larger the molecule/atom, the more electrons so greater electrostatic att’n, stronger v.d.w forces.

Question 23

Saturated/ unsaturated fats and v.d.w

Answer 23

Saturated fats have stronger v.d.w as they have straight chains so can fit together and form more v.d.w. Opposite for unsaturated as have a kink in chain.

Question 24

Dipole- dipole forces

Answer 24

• Occurs in permanently polar molecules
• Uneven distribution of electron cloud
• This means there is a delta positive and delta negative region to the molecule
• Interacts with other molecules, electrostatic att’n to opposite delta charge
• The greater the polarity of a bond or molecule, the stronger the permanent dipole-dipole interactions.

Question 25

Hydrogen Bonding

Answer 25

• Strongest IMF
• O, N or F bonded to H
• Lone pairs
• Attraction between H and lone pair on the delta negative region of other molecule (O,N or F)

Question 26

Electronegativity

Answer 26

The power of an atom to attract electron density in a covalent bond.

Question 27

Electronegativity trend

Answer 27

Down the group - decreases - increased shielding
Across the period - increases - nuclear charge increases - atomic radius decreases

Question 28

Polar Bond

Answer 28

Bond between atoms of elements with different electronegativities so that the electrons are asymmetrically distributed between the atoms.

Question 29

IMFs in water

Answer 29

More hydrogen bonding occurs causing a regular lattice arrangement of water molecules. Expands. Molecules are further apart than in liquid. Lower density so it floats.

Question 30

Include on h bonding diagram

Answer 30

Lone pairs
Delta charges
Dotted line