Bonding (P1) - Incomplete

Question 1

Ionic Bonding

Answer 1

Metal and non-metal

Electron transferred

Question 2

Properties of ionic compounds

Answer 2

Conduct electricity when molten or aqueous but not when solid - because ions are free to move and carry charge in the liquid state but not the solid

Solid at room temperature - giant structures mean they have high melting points and lots of energy is need to break up the lattice of ions

Brittle and shatter easily - Because they form a lattice of alternating positive and negative ions, so a blow produces contact between ions with like charges and they repel

Question 3

Covalent Bonding

Answer 3

Non-Metals

Electron sharing

Question 4

Co-ordinate Bonding (give example)

Answer 4

• An atom donates a lone pair of electrons
• An electron deficient atom accepts an electron pair
• NH4 (Ammonium ion)

Question 5

Metallic Bonding

Answer 5

Lattice of positive metal ions in a sea of delocalised electrons, electrostatic forces

Question 6

Properties of metals

Answer 6

Good conductors of heat and electricity - delocalised sea of electrons carries charge. an electron enters at the negative terminal and joins the sea of delocalised electrons just as one leaves at the positive terminal

Strong - Electrostatic forces extend throughout the structure and there are no individual bonds to break

Malleable and ductile - After small distortions the metal ions are still in the same environment as they were before, so the new shape is retained

High melting points - Giant structures, strong electrostatic forces that require lots of energy to break

Question 7

Electronegativity definition

Answer 7

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

Question 8

What does electronegativity depend on and why?

Answer 8

• The larger the nuclear charge the greater the electronegativity, stronger electrostatic forces
• The smaller the atomic radii the greater the electronegativity, less distance between the nuclei and shared electrons because of less electron shielding, stronger electrostatic forces

Question 9

Trends in electronegativity

Answer 9

Across a period - electronegativity increases

Down a group - electronegativity decreases

Question 10

Name the three types of intermolecular forces from order of weakest to strongest

Answer 10

van der Waals
Permanent dipole/Dipole-Dipole
Hydrogen bonding

Question 11

Give two examples of molecules where the dipoles cancel each other out

Answer 11

Carbon Dioxide - Linear

Tetrachloromethane - Tetrahedral

Question 12

What molecules do dipole-dipole forces occur between?

Answer 12

Two molecules with permanent dipoles

Question 13

How do van der Waals forces work?

Answer 13

Electron distribution is constantly shifting in an atom, meaning that a temporary dipole can occur. These temporary dipoles are weakly attracted to other temporary dipoles.

Question 14

What affect does increasing the number of electrons have on van der Waals forces?

Answer 14

Increases the strength, because more electrons means a larger temporary dipole

Question 15

When does hydrogen bonding occur? Give an example of a molecule where it occurs

Answer 15

1. A hydrogen atom that is bonded to a very electronegative atom (to produce a strong partial positive charge on the hydrogen atom)
2. A very electronegative atom with a lone pair of electrons (to attract the partially charged hydrogen atom)

Example: Water

Question 16

Boiling points of the hydrides

Answer 16

Add to later

Question 17

Structure and density of ice

Answer 17

• When water freezes the hydrogen molecules hold the molecules in a fixed position
• In order to fit into this structure the molecules are slightly less closely packed than in liquid water
• Therefore ice is less dense than water

Question 18

Electron pair repulsion theory

Answer 18

Electron pairs around an atom repel each other, and will therefore take up positions as far apart as possible from each other

Question 19

Two electron pairs

Answer 19

Linear, 180

Two block lines

Question 20

Three electron pairs

Answer 20

Trigonal planar, 120

Three block lines

Question 21

Four electron pairs

Answer 21

Tetrahedral, 109.5

Block line up, block line SW, triangle down, dotted line SE

Question 22

Five electron pairs

Answer 22

Trigonal bipyramid, 120 and 90

Block line up, down and left. Dotted line NE and triangle SE

Question 23

Six pairs of electrons

Answer 23

Octahedral, 90

Up and down block lines, upper two lines dotted and lower two lines triangle

Question 24

How does the lone pair in ammonia impact its molecule shape?

Answer 24

Repels the bonded electrons down (left triangle, down solid and right dotted)
Triangular pyramid

Question 25

How do lone pairs impact the molecular shape of water?

Answer 25

Repel the bonded electron pairs down
V-shaped
104.5

Question 26

What are the three shapes of molecules caused by lone pairs called? Give the electron pair numbers for each

Answer 26

V-shaped (2 bonded pairs, two lone pairs)
Triangular pyramid (3 bonded pairs, one lone pair)
Square planar (4 bonded pairs, two lone pairs)

Question 27

How do lone pairs impact the shape of ClF4- ?

Answer 27

Lone pairs up and down, upper dotted lines, lower lines triangles

Question 28

Repulsion between electron pairs from weakest to strongest

Answer 28

Bonding pair - Bonding pair
Lone pair - Bonding pair
Lone pair - Lone pair

Question 29

Molecular crystals (Covalent)

Answer 29

Covalent bonds hold the molecules together but don’t act between the molecules

• Crystals are soft and break easily
• Low melting point and sublimes easily
• Does not conduct electricity - no charged particles