• Matter- the stuff that makes up everything in the universe

• Element- A substance that cannot be broken down into other substances by chemical or physical means

• Compound- A substance made of two or more elements chemically combined

• Mixture- Two or more substances that are mixed together but not chemically combined

• Atom- The smallest particle of an element

• Molecule- A combination of two or more atoms that are bonded together

• ATOMS = BUILDING BLOCKS

• Atoms are the basis of chemistry. They are the basis for everything in the Universe.

• There are three basic parts of an atom. The parts are the electrons, protons, and neutrons.

• The protons and neutrons are always in the center of the atom.

• Scientists call the center of the atom the nucleus.

• The electrons are always found whizzing around the center in areas called orbitals.

Draw in your notebook

Draw in your notebook

This is a Bohr Model of an atom.

• The atom is made up of three parts:

• Proton(+)-Small, positively charged particles in the nucleus of an atom

• Neutron(0)-Small uncharged particle in the nucleus of an atom

• Electron(-)-a tiny, negatively charged, high-energy particle that moves in the space outside the

nucleus of an atom

Atomic Number

• The number of protons in the nucleus of an atom

• The identity of an atom is determined by the Atomic #

• Helium has 2 Protons, its atomic number is 2

The Periodic Table

Atomic Number

Atomic weight

How to find the # of Protons, Neutrons, & Electron

• Protons-Same amount as the atomic #

• Electrons- Same as the # of protons

• Neutrons- The atomic mass – the atomic #

NaSodiumSodium

23

Protons: 11Neutrons: 12Electrons: 1111

Atomic Mass

• The average mass of one atom of an element

Valence Electrons

• The number of electrons in the outermost orbit of an atom

Isotope

• An atom with the same number of protons and different number of neutrons (and therefore different atomic masses)

• Example: Carbon -12

Carbon -14

Examples of Carbon Isotopes