Atoms and Matter

• Chemistry-the study of matter and its properties.

• Matter-anything that has mass and volume (it takes up space)

  • Examples: organisms, air, metal

  • Nonexamples: light, ideas, feelings

  • All matter is made up of atoms

• Atoms-the smallest part of any element that still has all the properties of that element

Atoms are made of 3 different parts (each is a subatomic particle)

1. Protons-a particle located in the nucleus of an atom that has a positive charge and a mass of 1 AMU (atomic mass unit). Atoms of different elements have different numbers of protons.

   1. Carbon atoms ALWAYS have 6 protons and never any more or any less

   2. Oxygen atoms ALWAYS have 8 protons and never any more or any less

   3. Gold atoms ALWAYS have 79 protons and never any more or any less

2. Neutrons-a particle located in the nucleus of an atom that has no charge (neutral) and a mass of 1 AMU (atomic mass unit)

Electrons-a particle located outside the nucleus of an atom (in the electron cloud orbitals) that has a negative charge and no measurable mass

Determining the number of each type of subatomic particle

• Protons: Atomic number tells you the number of protons

• Electrons: Assume all atoms are neutral (no overall positive or negative charge)

  • This means that the # protons (+) = # electrons (-)

Neutrons: Atomic Mass - Atomic Number = # neutrons

Protons = 5 (Based on Atomic Number)

Neutrons = 6 (Atomic mass rounded to nearest whole number minus atomic number…

11-5 = 6)

Electrons = 5 (Because there are 5 protons...positive and negative charges must be equal.)