Atomic Sturcture | OCR A Level Chemistry

Where are protons and neutrons located in an atom?

In the nucleus

What is the relative mass and charge of an electron?

Relative mass of 1/1800 and a charge of -1

What does the atomic number (Z) represent?

The number of protons in the nucleus

How is the mass number (A) calculated?

The sum of the number of protons and neutrons

What is the formula to calculate the number of neutrons?

Mass number (A) minus atomic number (Z)

Define isotopes.

Atoms of the same element with the same number of protons but different numbers of neutrons

Why do isotopes have similar chemical properties?

Because they have the same electronic structure

Define relative isotopic mass.

The mass of one isotope compared to one twelfth of the mass of one atom of carbon-12

Define relative atomic mass.

The weighted mean mass of one atom compared to one twelfth of the mass of one atom of carbon-12

Define relative molecular mass.

The average mass of a molecule compared to one twelfth of the mass of one atom of carbon-12

What is the formula for relative atomic mass using percentage abundance?

Sum of (isotopic mass multiplied by percentage abundance) divided by 100

What is the formula for relative atomic mass using relative abundance?

Sum of (isotopic mass multiplied by relative abundance) divided by the total relative abundance

What are spectator ions in a chemical reaction?

Ions that do not change state or oxidation number during a reaction

When should brackets be used in a chemical formula?

When there is more than one of a compound ion in the formula

What is the charge of a sulfate ion?

-2

What is the charge of a phosphate ion?

-3

What is the charge of an ammonium ion?

+1

What is the charge of a hydroxide ion?

-1

What is the formula for calcium hydroxide?

Ca(OH)2

What is the formula for ammonium sulfate?

(NH4)2SO4

Why does the 160 m/z peak in a bromine mass spectrum have double the abundance?

Because there is double the probability of forming Br79-Br81 compared to the other isotopic combinations

What is the charge of a nitrate ion?

-1

What is the charge of a carbonate ion?

-2

What is the formula for phosphate?

PO43-

What is the formula for carbonate?

CO32-