Introduction to Atoms, Mixtures, and Noble Gases

This set of vocabulary flashcards covers the basics of atomic structure, electron configuration, types of chemical mixtures, and the properties of Group 18 noble gases.

Atom

The smallest building block that everything around us consists of, featuring a nucleus of protons and neutrons with electrons moving around it.

Proton

A positively charged particle located in the nucleus of an atom.

Neutron

A neutral particle located in the nucleus of an atom.

Electron

A negatively charged particle that moves in shells around the atomic nucleus.

Mass number

$$\text{Mass Number} = \text{protons} + \text{neutrons}$$

K-shell

The first electron shell closest to the nucleus, which can hold a maximum of $2$ electrons.

L-shell

The second electron shell, which can hold a maximum of $8$ electrons.

Valence electrons

The electrons located in the outermost shell of an atom that determine how the atom reacts with others.

Magnesium Oxide

The substance formed when magnesium ($2$ valence electrons) reacts with oxygen, producing heat and a strong white light.

Homogeneous mixture

A mixture that looks identical throughout because the substances are completely and evenly mixed, such as salt water.

Heterogeneous mixture

A mixture where the different substances can be seen or distinguished, such as sand in water.

Solution

A type of homogeneous mixture that appears uniform and clear, where the substances cannot be separated by sight.

Suspension (Uppslamning)

A cloudy mixture where solid particles are mixed in a liquid but not dissolved, often sinking to the bottom over time.

Emulsion

A temporary mixture of two liquids that do not naturally mix, such as oil and water.

Noble Gases (Group 18)

A group of stable, colorless, and odorless gases on the far right of the periodic table, including helium, neon, and argon.

Noble gas valence shell

These atoms have full outer shells, typically with $8$ valence electrons (except helium, which has $2$), making them very unreactive.