# data[].attributes.body
Definition: basic unit of a chemical element
Structure of an Atom
-contains protons, neutrons, and electrons
- centre of atom is the nucleus, containing protons and neutrons
- electrons are arranged around nucleus in energy levels or shells

# data[].attributes.body
Definition: theory that all matter is made up of tiny, indivisible particles or atoms
3 Parts
1) all matter is composed of atoms
2) atoms of the same element are the same; atoms of different elements are different
3) atoms combine in whole-number ratios to form compounds

# data[].attributes.body
Examples: air, helium, nitrogen, carbon dioxide, water vapor, hydrogen
Physical Properties
pressure, # of particles, temperature, volume
Inter-molecular Forces
-  kinetic energy of particles is great enough to overcome forces of attraction between them
- molecules move apart when they collide

# data[].attributes.body
Examples: lightning, solar winds, stars, gas inside neon signs and florescent lights
Physical Properties
no definite shape or volume, high temperature, radiating, very low density,
Inter-molecular Forces
- no molecules, instead charged particles, they ionize and give rise to ions and electrons
- more complicated that inter-molecular forces, each particle can create its own field and radiate

# data[].attributes.body
Examples: water, milk, juice
Physical Properties
almost incompressible, definite volume, no definite shape, flow from higher to lower level
Inter-molecular Forces
-kinetic energy of particles small enough so forces of attraction between them is enough to hold particles close
- molecules don't move apart

# data[].attributes.body
Examples: iron, aluminum, brass, lead, ice, walls, chair, glass
Physical Properties
density (lead, gold, mercury), volume, odor, shape, volume, color, melting point, boiling point, heat capacity, hardness
Inter-molecular Forces
- inter-molecular forces are strongest in solids
- kinetic energy small enough so forces of attraction between them is enough to hold particles close
- molecules don't move apart

# data[].attributes.body
A property of a substance that's observed during a reaction where the chemical composition or identity is changed.
Ex. toxicity, flammability, heat of combustion

# data[].attributes.body
Any property that is measurable. The value describes a state of a physical system.
Ex. color, smell, freezing point, boiling point

# data[].attributes.headline
Difference between element and compound?

# data[].attributes.subject
Difference between element and compound?

# data[].attributes.body
A compound contains atoms of different elements chemically combined together, while an element is a pure chemical substance made of the same type of atom.

# data[].attributes.headline
Difference between pure substances and mixtures?

# data[].attributes.subject
Difference between pure substances and mixtures?

# data[].attributes.body
Pure substance can't be separated into any other kinds of matter, where mixtures are a combination of two or more pure substances.