Matter, Particles, and Energy Changes

Matter

Anything that has mass and takes up space.

Not matter

Anything that has no mass and takes up no space, such as energy (including light, sound, and heat).

Solid

A state of matter in which particles are packed together in a fixed pattern, vibrate in place, and have a fixed shape and volume.

Liquid

A state of matter where particles are close but arranged irregularly, slide past each other, and take the shape of their container.

Gas

A state of matter where particles are far apart, move quickly in all directions, fill their container, and are easily compressed.

Diffusion

The process of particles moving through other particles.

Atom

The smallest building block of an element, described as being like a tiny Lego brick that is far too small to see.

Element

A pure substance made of only one kind of atom, with about $118$ known kinds arranged in the periodic table.

Chemical symbols

Shorthand notations used to represent elements, such as $Na$ for sodium, $Fe$ for iron, $Cu$ for copper, $Au$ for gold, and $Ca$ for calcium.

Molecule

A unit formed when two or more atoms are joined together, such as oxygen gas ($O_2$) or nitrogen gas ($N_2$).

Compound

A substance formed when different kinds of atoms are chemically joined, such as water ($H_2O$), carbon dioxide ($CO_2$), or methane ($CH_4$).

Energy

What makes matter change or move; it is never created or destroyed, only transformed from one type to another.

Kinetic energy

The energy possessed by moving objects, such as a roller coaster.

Potential energy

Stored energy due to an object's position or condition, such as a ball at the top of a hill.

Thermal energy

The energy associated with the random motion of particles, exemplified by a hot cup of tea.

Chemical energy

Energy stored in the chemical bonds between atoms, found in things like food and batteries.

Electrical energy

Energy resulting from the flow of moving charges, such as current running through a wire.

Light energy

Energy carried by light waves, produced by sources such as sunlight or a torch.

Sound energy

Energy carried by vibrations, such as those generated by a tuning fork.

Nuclear energy

Energy stored in the center (nucleus) of atoms, such as the energy powering the sun.

Melting

The change of state from solid ice to liquid water that occurs when energy is added.

Boiling

The change of state from liquid water to gaseous steam that occurs when energy is added.