Chemistry Concepts

Front

Elements

Back

are pure substances with atoms that have a certain number of protons.

Examples include oxygen (O), nitrogen (N), carbon (C), hydrogen (H), gold (Au), and aluminum (Al).

Front

Molecules

Back

are groups of two or more atoms that combine and share electrons.

All molecules are compounds, but not all compounds are molecules.

Front

Polar molecules

Back

have a negative charge on one end and a positive charge on the other end.

This characteristic affects how molecules interact with each other.

Front

Compounds

Back

are substances formed when two or more elements chemically combine.

Examples include table salt (NaCl), rust (Fe2O3), water (H2O), and carbon dioxide (CO2).

Front

Mixtures

Back

are combinations of two or more substances that aren’t chemically joined together.

Examples include lemonade, salad, steel, trail mix, and milk.

Front

Metals

Back

are dense, shiny (luster), ductile (wires), malleable (bendable), and good conductors.

Metals are typically solids at room temperature.

Front

Nonmetals

Back

are brittle, dull, poor conductors, and often gases at room temperature.

These properties distinguish nonmetals from metals.

Front

A chemical formula

Back

is a combination of symbols and numbers representing elements in a molecule.

It shows the types and numbers of atoms present.

Front

A subscript

Back

in a chemical formula indicates the number of atoms of an element in a molecule.

It is written below and to the right of a chemical symbol.

Front

A coefficient

Back

in a chemical formula tells how many molecules are present.

It is a whole number placed in front of a chemical symbol or formula.