Chemistry Set C - Extra stuff (foundational + extensions)

Where are protons found and what is their charge?

In the nucleus with a charge of 1+.

Where are neutrons found and what is their charge?

In the nucleus with no charge.

Where are electrons found and what is their charge?

In shells around the nucleus with a charge of 1−.

Relative mass of a proton

1

Relative mass of a neutron

1

Relative mass of an electron

Almost 0.

What is atomic number?

The number of protons in an atom.

What is mass number?

The total number of protons plus neutrons.

How is the neutron number calculated?

Mass number minus atomic number.

Why is a normal atom neutral?

It has equal numbers of positive protons and negative electrons.

What determines an element’s identity?

Its number of protons.

What is an isotope?

Atoms of the same element with the same proton number but different neutron numbers.

What is electronic configuration?

The arrangement of electrons in shells around the nucleus.

Shell capacities used for the first 20 elements

2 electrons in the first shell, then 8 in the second and 8 in the third at this level.

What are valence electrons?

Electrons in the outermost occupied shell.

Why do atoms gain, lose or share electrons?

To obtain a more stable full outer electron shell.

Why does sodium form Na⁺?

Its configuration is 2,8,1, so it loses one outer electron.

Why does magnesium form Mg²⁺?

Its configuration is 2,8,2, so it loses two outer electrons.

Why does calcium form Ca²⁺?

Its configuration is 2,8,8,2, so it loses two outer electrons.

Why does chlorine form Cl⁻?

Its configuration is 2,8,7, so it gains one electron.

Why does oxygen form O²⁻?

Its configuration is 2,6, so it gains two electrons.

Difference between O₂ and O²⁻

O₂ is a diatomic molecule while O²⁻ is one oxide ion with a 2− charge.

Why does losing negative electrons produce a positive ion?

The atom is left with more positive protons than negative electrons.

Why does gaining negative electrons produce a negative ion?

The atom then has more negative electrons than positive protons.

What is valency?

The combining capacity of an atom or ion.

How is valency related to a simple ion’s charge?

Valency is usually the size of the charge without the positive or negative sign.

Common charge of Group 1 ions

1+

Common charge of Group 2 ions

2+

Common charge of Group 13 ions such as aluminium

3+

Common charge of simple Group 15 ions

3−

Common charge of Group 16 ions

2−

Common charge of Group 17 ions

1−

What element is H?

Hydrogen.

What element is Na?

Sodium.

What element is K?

Potassium.

What element is Mg?

Magnesium.

What element is Ca?

Calcium.

What element is Al?

Aluminium.

What element is C?

Carbon.

What element is N?

Nitrogen.

What element is O?

Oxygen.

What element is F?

Fluorine.

What element is Cl?

Chlorine.

What element is S?

Sulfur.

What element is P?

Phosphorus.

What element is Br?

Bromine.

What element is I?

Iodine.

What does hepta- mean?

7

What does octa- mean?

8

What does nona- mean?

9

What does deca- mean?

10

Ammonium ion

NH₄⁺

Phosphate ion

PO₄³⁻

What is unusual about ammonium?

It is a positive polyatomic ion even though it contains no metal.

Difference between nitride and nitrate

Nitride is N³⁻ while nitrate is NO₃⁻.

Difference between phosphide and phosphate

Phosphide is P³⁻ while phosphate is PO₄³⁻.

How do metals generally behave with electrons?

They tend to lose outer electrons and form positive ions.

How do non-metals behave in ionic bonding?

They tend to gain electrons and form negative ions.

How do non-metals behave in covalent bonding?

They share electrons with other non-metals.

Typical physical properties of metals

Good conductors, usually shiny, malleable and ductile.

Typical physical properties of solid non-metals

Usually poor conductors, dull and brittle.

What does a Roman numeral in an ionic compound’s name show?

The charge of a metal ion that can form ions with different charges.

Copper(II) ion

Cu²⁺

Iron(II) ion

Fe²⁺

Iron(III) ion

Fe³⁺

Formula for copper(II) carbonate

CuCO₃

Formula for iron(III) oxide

Fe₂O₃

Why are Roman numerals not used for sodium or calcium?

Their common ion charges are fixed at Na⁺ and Ca²⁺.

Test for hydrogen gas

A lit splint produces a squeaky pop.

Test for oxygen gas

A glowing splint relights.

Test for carbon dioxide gas

Bubble it through limewater and the limewater turns milky.

Difference between a simple ion and a polyatomic ion

A simple ion contains one atom while a polyatomic ion contains a bonded group of atoms with an overall charge.

Why can’t nitrate’s charge be found using basic shell configurations?

Nitrate is a bonded polyatomic ion whose overall charge must be memorised or supplied.

What should be used to construct salts efficiently?

Known ion charges rather than recalculating every electronic configuration.