Download Atomic Structure (Isotopes now not needed for Level 1)

Atoms
1. All substances are made from atoms.
2. There are about 100 different types of
atoms
3. An element is a substance which
contains only one type of atom
The Periodic Table
Element, Compound, Mixture
Structure of an Atom
1. Atoms have a small central nucleus
containing protons and neutrons
2. Electrons orbit the nucleus
3. Protons, neutrons and electrons have
different masses and charges
Atomic structure
Atomic structure
Atomic number
1. The atomic number is the number of
protons in the nucleus
2. In an atom, the number of electrons
always equals the number of protons
3. Atoms do not have an overall electrical
charge
Atomic number
Mass number
1. The mass number is the total number
of protons and neutrons in an atom
2. The number of neutrons can be
calculated by subtracting the atomic
number from the mass number
Mass number
Calculations
Isotopes
1. Isotopes are atoms of the same
element that have different numbers of
neutrons (e.g. carbon-12 and carbon14)
2. Isotopes have the same atomic
number but different mass numbers
Isotopes
Electrons
1. Each electron in an atom is at a
particular energy level (or shell)
2. Electrons fill the lowest energy levels
first (nearest to the nucleus)
3. The first shell can take a maximum of 2
electrons, the second shell can take 8,
and the third shell can take 8
Electron Shells
Electron arrangements
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