1.3 Bonding

Question 1

What is ionic bonding

Answer 1

Strong electrostatic forces of attraction between oppositely charged ions in a lattice

Question 2

Properties of ionic compounds and why

Answer 2

High mtp - lots of energy needed to break strong electrostatic forces of attraction between oppositely charged ions
Conducts electricity - only when molten/in solution, ions are free to move and carry charge

Question 3

What is simple molecular covalent bonding

Answer 3

Strong covalent bonds between atoms, weak van der waals forces of attraction between molecules

Question 4

Properties of simple molecular covalent molecules

Answer 4

Can’t conduct electricity - all electrons used in bonding - not free to move
Low mtp - weak van der waals forces of attraction between molecules that don’t take much energy to overcome

Question 5

Describe giant (macromolecular) covalent bonding

Answer 5

Giant lattice of many atoms held together by strong covalent bonds

Question 6

Properties of giant covalent bonding

Answer 6

High mtp - lots of energy to overcome strong covalent bonds
Most dont conduct electricity - electrons used in bonding

Question 7

Describe metallic bonding

Answer 7

Lattice of positive metal ions strongly attracted to a sea of delocalised electrons

Question 8

Properties of metallic bonding

Answer 8

Malleable - layers can slide over each other
High mtp - strong forces of attraction between positive metal ions and negatively charged sea of electrons
Conduct electricity - delocalised electrons can move throughout the structure and carry charge

Question 9

How does the strength of metallic bonds change across periodic table and why

Answer 9

Increases –> higher mtp and bp, stronger
Higher charge on metal ions
More delocalised electrons per ion
Stronger force of attraction between them

Question 10

Define electronegativity

Answer 10

The ability of an atom to attract the pair of electrons in a covalent bond

Question 11

What affects electronegativity

Answer 11

Nuclear charge
Atomic radius
Electron shielding

Question 12

Most electronegative element

Answer 12

Fluorine - largest nuclear charge for its electron shielding, small atomic radius

Question 13

How do you get a non polar bond

Answer 13

Both bonding elements have the same electronegativities

Question 14

When do you get a polar bond

Answer 14

Bonding atoms have different electronegativities

Question 15

Strongest imf

Answer 15

Hydrogen bonds

Question 16

Describe van der waals forces of attraction

Answer 16

Temporary dipoles are created by the random movement of electrons –> induces dipole in neighbouring molecule –> temporary induced dipole-dipole attraction

Question 17

Why are van der waals forces stronger in larger molecules

Answer 17

More electrons

Question 18

Describe permanent dipole-dipole attraction

Answer 18

Some molecules with polar bonds have permanent dipoles –> forces of attraction between those dipoles and those of neighbouring molecules

Question 19

What conditions are needed for hydrogen bonding to occur

Answer 19

H bonding to either O,N,F, lone pair of electrons on O, F, N
As O,N and F are highly electronegative, H nucleus is left exposed
Strong force of attraction between H nucleus and lone pair of electrons on O,N,F

Question 20

Why is ice less dense than liquid water

Answer 20

In liquid water, hydrogen bonds constantly break and reform as molecules move about
in ice, the hydrogen bonds hold the molecules in fixed positions; this makes them slightly further apart than in liquid water

Question 21

What is a dative covalent bond and when is it formed

Answer 21

Formed when an electron deficient atom/ion accepts a lone pair of electrons from an atom/ion with a lone pair of electrons

Question 22

What does the shape of molecules depend on

Answer 22

Number of electrons in the valence shell of the central atom
Number of these electrons which are in bonded or lone pairs

Question 23

What does the electron pair repulsion theory state

Answer 23

That electron pairs will take up positions as far away from each other as possible, to minimise the repulsive forces between them

Question 24

Shape and angle of 2bp

Answer 24

Linear
180

Question 25

Shape and angle of 3bp

Answer 25

Trigonal planar
120

Question 26

Shape and angle of 4bp

Answer 26

Tetrahedral
109.5

Question 27

Shape and angle of 5bp

Answer 27

Trigonal bipyramid
90 and 120

Question 28

Shape and angle of 6bp

Answer 28

Octahedral
90