1. Atoms
UNIT 2 – Lesson 2 Notes

2. Matter All matter is made up of tiny particles called atoms.
There are many different types of atoms. Most things are a mixture of atoms. 2

3. Matter Elements are pure substances made up of only ONE type atom.
They are the simplest form of matter!
Living things are not ELEMENTS, because they are made up of a combination of atoms:
Oxygen
Carbon
Hydrogen
Nitrogen
Sulfur
Phosphorus 3

5. Identify an Element
So many to choose from…

7. Building Blocks proton neutron electron
Three basic particles make up an atom: protons, neutrons, and electrons.
Protons and neutrons make up the nucleus of an atom.
Electrons orbit around the nucleus.
proton
neutron
electron

8. Building Blocks _ + cHaRgEs + _
Protons – particles that have a positive electric charge (+)
Neutrons – particles that have a no electrical charge (0)
The nucleus has a positive charge
Electrons – particles that have a negative charge (-) _ + +
cHaRgEs + _

9. Building Blocks The number of protons determines what element it is!
When you add protons to the nucleus, you change the element.

10. Reading the Periodic Table
Atomic number – the number of protons in an atom’s nucleus.
Each element has a certain atomic number.
This also equals the number of electrons in the atom’s electron cloud.
Atomic Number
Element

11. Reading the Periodic Table
Atomic Mass– the number of protons and neutrons making up an atom’s nucleus.
Atomic Number
Element
Atomic Mass 11

12. Atomic Number Element Atomic Mass
number of protons as well as electrons
Element
Atomic Mass
number of protons and neutrons combined

13. Isotopes
Isotopes – atoms of the same element that have different numbers of neutrons.
proton
neutron
electron

14. About Electrons
Electron shells are the “clouds” around the nucleus where the electrons move.
The first shell can only hold 2 electrons
Shells outside of the first can hold 8 electrons
The outer most shell is called the valence shell Na 14

16. Simple Science:
What is an ATOM
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