Science

The definition of an atom

Is the smallest unit of matter, consisting of a nucleus made up of protons and neutrons, surrounded by electrons that orbit the nucleus.

The definition of an element

A pure substance made of only one type of atom.

The definition of a compound

A substance formed when two or more different elements chemically combine in fixed proportions.

The definition of a mixture

A material made up of two or more different substances that are physically combined and can be separated by physical means.

The differences between an atom, element, compound and mixture

• Atom: single unit of matter.
• Element: many identical atoms.
• Compound: chemically bonded different elements.
• Mixture: physically combined substances.

Metal VS Non-Metal elements

Metals: shiny, good conductors, malleable.
Non‑metals: dull, poor conductors, brittle.

What is a metalloid?

An element with properties of both metals and non‑metals.

How to write and understand compound names

Write the first element’s atomic name followed by the second element’s atomic name.

Physical VS chemical mixing

Physical mixing: substances retain their original identities and can be separated physically.
Chemical mixing: new substances with new properties are formed.

The different possible type of mixture combinations

Homogeneous mixtures (uniform throughout, e.g., salt water) and heterogeneous mixtures (distinct phases, e.g., oil‑water).