Examples of certain chemical elements. From left to right: hydrogen, barium, copper, uranium, bromine, and helium.
A element is a pure substance made of one type of atom
Elements are divided into metals and non-metals
Examples of non-metal elements include carbon, oxygen, hydrogen, and nitrogen
Examples of metal elements include aluminum, iron, copper, and gold
A gold bar
All the matter we can see is made of very small particles called ‘atoms.’
They are not the smallest things we know of, but they are so small we can’t see them except with the most powerful microscopes. (A microscope is a tool for looking at very small things.)
There are about 5.07 x 1024 or 5,070,000,000,000,000,000,000,000 atoms in a milliliter of water.
All atoms are made up of just 3 basic particles:
“Charge” causes objects to experience a force when near other electrically charged objects. It’s like a magnet.
An atom has a nucleus in the middle, and electrons around the nucleus
The nucleus is made of protons and neutrons
An atom has the same number of protons as electrons so the + and - charges cancel to equal 0 charge for the atom
A helium atom
Question: Is the nucleus’ charge positive or negative?
The elements on our planet were mostly made before the Earth was made
The simplest elements, hydrogen and helium, were created when the universe was created
The other elements were made inside stars which later exploded
Most of your body’s atoms were made inside stars billions of years ago
Some elements we need to stay alive, like oxygen. Oxygen is in air, and we would die in minutes without it
Other elements are very poisonous and even a small amount would kill us, like arsenic
A molecule is a group of atoms that have joined together into one piece.
Molecules have 2 or more atoms in them, and some molecules have thousands or more atoms in them.
Here are some common molecules:
Carbon Dioxide: CO2