Electrons, bonding and shapes

Question 1

What sub shells are there?

Answer 1

s, p, d, f

Question 2

What is an s orbital?

Answer 2

Sphere shape, up to 2 electrons

Question 3

What is a p orbital?

Answer 3

Dumbell shape, each shell above n= 2 has 3 p orbitals.

Question 4

How do orbitals fill?

Answer 4

In order of increasing energy. Fill singly before sharing with opposite spins.
4s before 3d ALWAYS

Question 5

What is the order of orbitals?

Answer 5

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6

Question 6

What is ionic bonding?

Answer 6

The electrostatic attraction between positive and negative ions.

Metal and non metal

Question 7

What are properties of ionic bonding?

Answer 7

High melting/boiling point - solid at room temp as insufficient energy to overcome strong electrostatic forces - lots of energy
Soluble - dissolve in polar solvents as break down lattice + surround each ion
Conduct - when molten/dissolved but not solid as ions in fixed positive lattice without mobile charge carriers

Question 8

What is covalent bonding?

Answer 8

Many electrostatic attraction between shared pair of electrons and nuclei of bonded atoms.

Question 9

How does covalent bonding occur?

Answer 9

Overlap of atomic orbitals, each with 1 electron to give a shared pair, which is attracted to both nuclei. Bonded atoms often have outer shells with same electrons as the nearest noble gas.

Question 10

What is a molecule?

Answer 10

The smallest part of a covalent compound retaining chemical properties of the compound.

Question 11

What are exceptions to normal outer electron shells?

Answer 11

• Boron trifluoride, boron only has 6 electrons in the outer shell
• Sulfur hexafluoride, sulphur has 12 electrons in outer shell

Question 12

What is a dative covalent bond?

Answer 12

Shared pair of electrons have been supplied by 1 atom only.

Question 13

What causes shapes of molecules?

Answer 13

Electrons repel, so they arrange themselves as far away as possible from each other. A lone pair is slightly closer to the central atom and occupies more space and repel more.

Question 14

When does the position of electrons in a bond change?

Answer 14

• Nuclear charges are different
• Atoms may be different sizes
• Shared pair of electrons may be closer to 1 nucleus

Question 15

What is the Pauling scale for?

Answer 15

To compare electronegativity of atoms of different elements. Across the periodic table, nuclear charge increases and atomic radius decreases.

F is the most electronegative.

Question 16

How does a polar bond form?

Answer 16

The bonded electron pair share unequally between bonded atoms. Different bonded atoms with different electronegativity.

Question 17

What are intermolecular forces?

Answer 17

Weak interactions between dipoles if different molecules.
3 types: hydrogen bonding, permanent dipole interactions, induced dipole interactions.

Question 18

What are London’s forces?

Answer 18

Weak intermolecular forces that exist between all molecules.

Question 19

How are London’s forces formed?

Answer 19

Movement of electrons produces a changing dipole in a molecule. At any time, an instantaneous dipole will exist. Induces dipole on neighbouring molecule. (like dominoes).

Question 20

What happens as the number of electrons in each molecule increases?

Answer 20

The larger the instantaneous induced dipole, the greater the dipole interactions and the stronger the attractive forces between molecules.

Question 21

What are properties of simple molecules?

Answer 21

Simple molecular lattice with weak forces and strong covalent bonds.
- low melting/boiling point
- soluble in non-polar solvent

Simple polar molecules dissolve in polar substances only.

Question 22

What is a hydrogen bond?

Answer 22

Strongest type of permanent dipole interaction.

Formed between N, O, F and hydrogen atom attached to one of the above.