Electron Structure

Question 1

What is the shape of an s-orbital?

Answer 1

Spherical, check cgp

Question 2

What shape are p-orbitals?

Answer 2

Dumbbell shape, check cgp

Question 3

For orbitals with the same energy how do they fill up orbitals?

Answer 3

Singly before they start sharing

Question 4

Define ionic bond

Answer 4

The electrostatic attraction between two oppositely charged ions

Question 5

Draw a dot and cross diagram for MgCl2

Answer 5

Check cgp

Question 6

What is a giant ionic structure? Give an example as well

Answer 6

NaCl - cube shaped - Very strong ionic bonds, so it takes a lot energy to break up the lattice.

Called ‘giant’ because it is made up of the same basic unit repeated over and over again
Each ion is electrostatically attracted in all directions to ions of the opposite charge.

Question 7

In what state can ionic compounds conduct electricity in?

Answer 7

Molten or dissolved, but no solid. Ions in a liquid are mobile (can carry charge). In solid they are fixed in position by strong ionic bonds.

Question 8

Why do ionic compounds have high melting and boiling points?

Answer 8

the giant ionic lattices are held together by strong electrostatic forces. It takes load of energy to overcome these forces, so melting and boiling points are very high.

Question 9

Why can ionic compounds dissolve in water?

Answer 9

Water molecules are polar - part of the molecule has a small negative charge, and the other bits have small positive charges. The molecules are attracted to the charged ions. They pull the ions away from the attic causing it to dissolve.

Question 10

Define covalent bond

Answer 10

A strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms

Question 11

Construct a dot and cross diagram for as single covalent bond. H2O

Answer 11

Check cgp

Question 12

Draw a covalent bond for boron triflouride.

Answer 12

Check cgp

Question 13

Draw a covalent bond for sulfur hexaflouride

Answer 13

Check cgp

Question 14

Define dative covalent bond

Answer 14

A type of covalent bond in which both the electrons in the shared pair come from one atom

Question 15

Construct a diagram for a dative covalent bond

Answer 15

Forms when nitrogen atom in an ammonia molecule doantes a pair of electrons to a proton (H+)

Question 16

How is the strength of a covalent bond shown?

Answer 16

The average bond enthalpy. Measures the energy required to break covalent bonds. Stronger the bond more energy is required to break it so the greater the value of average bond enthalpy

Question 17

how many bonding pairs, bond angles and lone pairs are there in a linear molecule. Give an example too.

Answer 17

2
180
0

Cl - Be - Cl
Or
CO2

Question 18

how many bonding pairs, bond angles and lone pairs are there in a non linear (bent) . Give an example too

Answer 18

2
104.5
2

H2O

Question 19

how many bonding pairs, bond angles and lone pairs are there in a tignonal planar molecule. Give an example too

Answer 19

3
120
0

BF3

Question 20

how many bonding pairs, bond angles and lone pairs are there in a trigonal pyramidal molecule. Give an example too

Answer 20

3
107
1

NH3
Or
PF3

Question 21

how many bonding pairs, bond angles and lone pairs are there in a tetrahedral molecule. Give an example too

Answer 21

4
109.5
0

CH4
NH4+

Question 22

how many bonding pairs, bond angles and lone pairs are there in a trigonal bipyramidal bmolecule. Give an example too

Answer 22

5
90 and 120
0

PCl5

Question 23

how many bonding pairs, bond angles and lone pairs are there in a octahedral molecule. Give an example too

Answer 23

6
90
0
SF6

Question 24

Explain how electron pair repulsion works?

Answer 24

lone pairs repel more than bonded pairs and the bond angles.
Electron pairs repel each other as far as possible.

Question 25

Define electronegativity

Answer 25

The ability of an atom to attract the bonding electrons in a covalent bond. fluorine is the most electronegative element.

Question 26

Define a dipole

Answer 26

A difference in charge between two atoms caused by a shift in electron density in the bond.

Question 27

What is the polarity like in covalent bonds in diatomic gases?

Answer 27

Non-polar because the atoms have equal negativities and so electrons are attracted to both nuclei. Same with carbon and hydrogen because they have similar electronegativities.

Question 28

Hoe can a bond be more polar?

Answer 28

When there’s a greater difference in electronegativity.

Question 29

How is a permanent dipole formed?

Answer 29

The difference in electronegativity between two atoms.

Question 30

How can a molecule have an overall dipole?

Answer 30

If the polars bonds are arranged so that they don’t cancel each other out then charge is arranged unevenly across the whole molecule. overall dipole molecules are polar. E.g. water. Molecule wont have an overall dipole if the polar bonds are arranged symmetrically so that dipoles cancel each other out. No overall dipole means non-polar.

Question 31

What are the 3 intermolecular forces. They are weak

Answer 31

1) induced dipole-dipole (London forces) 2) permanent dipole-dipole interactions 3) hydrogen bonding (strongest)

Question 32

What are induced dipole-dipole forces?

Answer 32

Affects all atoms and molecules Atoms form temporary dipoles. dipole can cause another temporary (induced) dipole in the opposite direction on a neighbouring atom. Two dipoles are attracted to each other. Dipoles are being created and destroyed all the time and create and overall effect of atoms being attracted to each other.

Question 33

What affect does London forces have on boiling points?

Answer 33

When boiling a liquid you need to overcome the intermolecular forces. More energy required to overcome stronger London forces. So higher boiling points. Molecules with greater surface areas affected.

Question 34

Explain how induced dipole-dipole forces can hold molecules in a lattice for I2

Answer 34

Iodine atoms held together in pairs by strong covalent bonds to form molecules of I2. Molecules then held together in a molecular lattice arrangement by weak induced dipole-dipole interactions.

Question 35

What are permanent dipole-dipole interactions?

Answer 35

Polar molecules cause weak electrostatic forces of attraction between molecules. Happen in addition to induced dipole-dipole interactions

Question 36

What are hydrogen bonds?

Answer 36

Only happens when hydrogen is covalently bonded to fluorine, nitrogen or oxygen. Bond is so polarised that weak bonds form between hydrogen and e.g. oxygen.

Question 37

Compare the density of ice with water.

Answer 37

Molecules of H2O held in lattice by hydrogen bonds. Ice melts hydrogen bonds are broken. As there are more hydrogen bonds in ice than water, and hydrogen bonds are long, it makes ice less dense than water

Question 38

Why do hydrogen bonds make molecules have higher melting and boiling points?

Answer 38

Extra energy required to break the hydrogen bonds.

Question 39

What is the main intermolecular force that determines the boiling point of a substance?

Answer 39

The strength of the induced dipole-dipole (London) forces. Unless the molecule can form hydrogen bonds. e.g. for group7 hydrides from HCl to HI - although the permanent dipole dipole interactions are decreasing, the number of electron is increasing so the strength of the induced dipole-dipole interactions also increases. But if two molecules have similar number of electrons, the more polar bond will have stronger permanent dipole-dipole interactions and so a higher boiling point.

Question 40

What are simple molecular structures?

Answer 40

Molecules that consist of covalently bonded molecules with induced dipole-dipole (London) forces. Very weak and requires not much energy to overcome them, meaning simple molecular structures have low melting and boiling points. Very poor conductors as their structures don’t contain any charged particles.