Atomic Structure & Radioactivity

State the three subatomic particles found in an atom.

Protons, neutrons, electrons.

Where in the atom are protons and neutrons located?

In the nucleus.

What is the relative mass of a proton?

1

What is the relative charge of a neutron?

0 (neutral).

What is the relative charge of an electron?

–1.

Compare the relative mass of a proton and an electron.

Proton: 1, Electron: 1/1836.

Why is an atom electrically neutral?

Because the number of protons (+1 each) equals the number of electrons (–1 each), cancelling out the charges.

Which subatomic particle moves around the nucleus?

Electrons.

What is the relative mass of a neutron?

1

The further an electron shell is from the nucleus, the ___ its energy.

Higher.

What is the maximum number of electrons in the first shell?

2.

What is the maximum number of electrons in the second shell?

8.

For the first 20 elements, what is the maximum number of electrons in the third shell?

8.

Beyond calcium, how many electrons can the third shell hold?

Up to 18.

What is the simplest atom?

Hydrogen.

What is the relative atomic mass of carbon?

12.0.

Define isotopes.

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

What is the natural abundance ratio of chlorine-35 to chlorine-37?

75% : 25%.

Isotopes of the same element have the same ___ properties.

Chemical.

Isotopes of the same element have different ___ properties.

Physical.

Define nuclear decay.

A random and spontaneous process where an unstable nucleus loses energy by emitting radiation.

What are the three types of nuclear radiation?

Alpha (α), beta (β), gamma (γ).

What particle is identical to a helium-4 nucleus?

An alpha particle.

What type of particle is a fast-moving electron?

A beta particle.

What type of radiation is electromagnetic radiation?

Gamma radiation.

What is conserved during nuclear decay?

Mass number and charge.

What is nuclear fission?

Splitting of a nucleus into two parts, releasing energy.

What is nuclear fusion?

Two light nuclei combine to form one heavier nucleus, releasing energy.

What is the valence shell?

The outermost electron shell that contains at least one electron.

What happens when an atom loses electrons?

It becomes a positively charged cation.

What happens when an atom gains electrons?

It becomes a negatively charged anion.

What is an alpha particle?

An alpha particle is a helium nucleus consisting of 2 protons and 2 neutrons, with a charge of +2 and a relative mass of 4.

What is an beta particle?

A beta particle is a high-speed electron with a –1 charge and negligible mass, emitted when a neutron changes into a proton in the nucleus.

What is gamma radiation?

Gamma radiation is high-energy electromagnetic radiation with no mass and no charge, emitted from an excited nucleus. It does not change the proton or nucleon number.