Matter & Chemistry
Properties of matter, periodic table, and chemical changes
In this lesson:
Elements
An element is a pure substance that cannot be broken down into simpler substances by chemical means. Elements are the building blocks of all matter.
Examples: Hydrogen, Oxygen, Carbon, Gold, Iron
The periodic table organizes all known elements
Compounds
Compounds are pure substances formed when two or more elements chemically combine in a fixed ratio. Compounds can only be separated by chemical means.
Examples: Water (Hâ‚‚O), Carbon Dioxide (COâ‚‚), Table Salt (NaCl)
Water (Hâ‚‚O) is a compound made of hydrogen and oxygen atoms
The Periodic Table
The periodic table organizes all known elements based on their properties. Elements in the same column (group) have similar properties.
The periodic table was developed by Dmitri Mendeleev in 1869.
A period on the periodic table is a horizontal row.
Did You Know?
The most abundant element in the universe is hydrogen, making up about 75% of all matter!
Quick Check: Which of these is an element?
Drag each item to the correct category
Explore a Water Molecule
Click and drag to rotate the 3D model of a water molecule
