Topic 1&2

What is the mass of a proton

1

What is the mass of an electron

0

What is the mass of a neutron

1

What is the charge of a proton

+1

What is the charge of an electron

-1

What is the charge of a neutron

0

What is the atomic number

Number of protons

What is the mass number

Sum of protons and neutrons

What are isotopes

Atoms of the same element that have the same number of protons but different numbers of neutrons

Define relative isotopic mass

Mass of an atom of an isotope of the element compared to 1/12th of a carbon-12 atom

Define relative atomic mass

Average mass of the atoms of that element compared to the mass of 1/12th of a carbon-12 atom

How can mass spec be used to determine Mr

The peak with the highest m/z value is the molecular ion peak which is equal to the Mr of the compound

Define first ionisation energy

Energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous positive ions

Define successive ionisation energies

The energy required to remove electrons from an atom or ion one after another

How are ionisation energies affected by nuclear charge

The more protons there are in the nucleus, the more positively charged the nucleus is and the stronger the attraction for the electrons

How are ionisation energies affected by electron shielding

As the number of electrons between the outer electrons and nucleus increases the outer electrons will feel less attraction

How are ionisation energies affected by the sub-shell that the electron is in

An electron close to the nucleus will be more strongly attracted to one in a shell further away

Why do first ionisation energies increase across a period

The nuclear charge increases, there is no significant change in atomic radius, the shielding remains the same

Why do first ionisation energies decrease down a group

Elements down a group have extra electron shells so the atomic radius is larger and outer electrons are further away from the nucleus which reduces the attraction. The extra inner shells shield the outer electrons

How many electrons can fill the first four shells

2, 8, 18, 32

What is an orbital

A region within an atom that can hold up to two electrons with opposite spins

What shape is an s-orbital

Spherical

What shape is a p-orbital

Dumb-bell

How many electrons occupy s subshells

2

How many electrons occupy p subshells

6

How many electrons occupy d subshells

10

How do electrons fill subshells

Fill subshells singly before pairing up

What is periodicity

Regular repeating patterns across different periods

How do the melting and boiling points of group 2&3 depend on structure and bonding

As you go across a period the type of bond formed changes, for the metals melting and boiling points increase because the metallic bonds get stronger (due to increased delocalised electrons and decreasing radius), elements with giant covalent lattice structure have strong covalent bonds which require a lot of energy to break, simple molecular structure melting and boiling points depend on the strength of the London forces which are weak and easily overcome (more electrons mean stronger London forces)

Define ionic bonding

Strong electrostatic attraction between oppositely charged ions

How do ionic radius and charge affect strength of ionic bonding

The greater the charge on an ion the stronger the ionic bond and therefore higher melting/boiling point. Smaller ions can pack closer together (electrostatic attraction gets weaker with distance), so smaller ions have stronger ionic bonding

How do ions form

When electrons are lost or gained

What is the trend for ionic radii down a group

Ionic radius increases as atomic number increases because extra electron shells are added

What are isoelectronic ions

Ions of different atoms with the same number of electrons

What happens to the ionic radii down a group for isoelectronic ions

The ionic radius decreases because the number of electrons stays the same but the number of protons increases so the electrons are attracted to the nucleus more strongly pulling them in more

What is a covalent bond

Strong electrostatic attraction between two nuclei and the shared pair of electrons between them

What is the relationship between bond lengths and strengths in covalent bonds

The higher the electron density the stronger the attraction between the atoms, the higher the bond enthalpy and the shorter the bond length.

How do molecules and ions get their shape

Determined by the repulsion between the electron pairs that surround the central atom

What is electronegativity

Ability of an atom to attract the bonding pair of electrons in a covalent bond

What do electronegativity differences lead to

Bond polarity

How do London forces work

At any particular moment the electrons in an atom are more likely to be more on one side than the other producing a dipole, this dipole can induce another temporary dipole.

What effects do permanent dipoles have

Higher melting and boiling points

How do hydrogen bonds work

Hydrogen has a high charge density so hydrogen atoms form weak bonds with lone pairs of electrons on F,N, or O atoms

Why can HF, NH3, and H2O form hydrogen bonds

They are very electronegative so draw the bonding electrons away from the hydrogen atom

How does hydrogen bonding cause water to have high melting and boiling points

Water can form hydrogen bonds with itself which causes a high boiling point

How does the density of ice and water differ

In ice the water molecules are arranged so that there is the maximum number of hydrogen bonds making it less dense than water

How does the boiling point change in alkanes with longer chains

Boiling point increases as chain length gets longer as they can form more London forces

What effect does branching have on alkane boiling temp

Boiling point decreases as branching increases because branching decreases surface area so there are fewer London forces

Why are alcohols less volatile than alkanes

All alcohols contain a polar hydroxyl group which can form hydrogen bonds. Hydrogen bonding gives alcohols low volatilities.

What is the trend with boiling points of hydrogen halides

HF has the highest boiling point due to its ability to produce hydrogen bonds, the boiling point then decreases down the group from HCl to Hi because the halogens increase in size so the London forces are stronger

What is metallic bonding

Strong electrostatic attraction between metal ions and delocalised electrons

Where are giant lattices present

Ionic solids, covalently bonded solids, solid metals

What type of solvent do ionic substances dissolve in, give an example

Polar solvents, water

In what type of solvent do alcohols dissolve in, give example

Polar solvents, water

Why can't halogenoalkanes with polar bonds dissolve in water

The hydrogen bonding between water molecules is stronger than the bonds that would be formed with halogenoalkanes