IB Chemistry SL Structure 1.2

Subatomic particles

Particles that make up an atom: protons, neutrons, and electrons.

Relative atomic mass

Mass of subatomic particles compared to each other.

Proton

A subatomic particle with a relative charge of +1 and a relative mass of 1.

Neutron

A subatomic particle with a relative charge of 0 and a relative mass of 1.

Electron

A subatomic particle with a relative charge of -1 and a negligible mass.

Nucleus

The positively charged center of an atom containing protons and neutrons.

Electrostatic attraction

The force that holds electrons in orbit around the nucleus.

Atomic number (Z)

The number of protons in the nucleus of an atom.

Mass number (A)

The total number of protons and neutrons in the nucleus of an atom.

Isotopes

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

Atomic structure

The arrangement of subatomic particles within an atom.

Neutral atom

An atom with an equal number of protons and electrons.

Ion

A charged particle that has gained or lost electrons.

Relative charge of a proton

+1.

Relative charge of a neutron

Relative charge of an electron

-1.

Number of neutrons

Calculated by mass number - atomic number.

Chemical symbol of an element

A notation consisting of one or two letters representing an element.

Balanced charge in a neutral atom

Number of protons equals the number of electrons.

Percentage abundance

The relative amount of an isotope in a sample.

Relative atomic mass (Ar) definition

The average mass of one atom of an element compared to one twelfth of the mass of an atom of carbon-12.

Atomic model

A visual representation showing the nucleus and electron arrangement.

Mg2+ ion

A magnesium ion with a charge of +2, meaning it has lost two electrons.

Carbon atom

An atom with an atomic number of 6, containing 6 protons and 6 electrons.

Mass of a proton

Assigned a relative mass of 1.

Mass of an electron

Considered negligible compared to protons and neutrons.

Formation of a positive ion

Occurs when an atom loses one or more electrons.

Formation of a negative ion

Occurs when an atom gains one or more electrons.

Relative atomic mass calculation

Total mass of isotopes divided by total number of isotopes.

Copper

Element X with 29 protons and mass number 63.

Carbon-12

An isotope of carbon containing 6 protons and 6 neutrons.

Carbon-14

An isotope of carbon containing 6 protons and 8 neutrons.

Mass of oxygen isotopes example

Calculating the relative atomic mass using percentage abundances.

Formula for calculating neutrons

Number of neutrons = mass number (A) - number of protons (Z).

What does it mean to be an isotope?

Same element with the same number of protons but different number of neutrons.