1. Atoms: Building Blocks of Matter
Chapter 4
Atoms: Building Blocks of Matter

2. Section 4-1
Structure of the Atom

3. Structure of the Atom Subatomic particles make up atoms.
3 main Particles.
1. Protons
2. Neutrons
3. Electrons

4. Protons Positively charged particle. Found in the nucleus.
Has the mass of 1 atomic mass unit. (very small)
It takes 600,000,000,000,000,000,000,000 protons to make 1 gram.

5. Neutrons Electrically neutral. Found in the nucleus.
Mass of 1 atomic mass unit (amu).

6. Protons and Neutrons Found in the nucleus.
Both particles are at the center of the atom.
Extremely small.
Make up 99.9% of the mass of the atom.
Positively charged.
Size of a bee in a football stadium.

7. Electrons Negatively charged particle.
Found outside of the nucleus in the electron cloud.
Region where there is the most likely hood of finding an electron.
The probable location of an electron in an electron cloud will depend on how much energy the electron has.

8. Electrons
Mass of amu.
Remember the shells or clouds are in energy levels.
Lowest levels is closest to the nucleus.
Highest is farthest away from the nucleus.

9. Energy Levels
Energy levels can only hold a limited number of electrons.
1st- 2 electrons max
2nd- 8 electrons max
3rd- 18 electrons max
4th- 32 electrons max
The chemical properties of elements depend on how the electrons are arranged in the atom.

10. Energy Levels
Each level has a specific Energy and if an electron loses or gains Energy it can move to different Energy levels.
When this happens, they give off light (it jumps up when it gains and down when it loses. The energy is light.)

11. Na Periodic Table Atomic Number Chemical Symbol Name of the Element
Atomic Mass 11 Na
Sodium
22.990 A B C D

12. Periodic Table The atomic number- the number of protons in the atom.
It is the number of protons in an atom that makes it the element it is.
Isotopes are atoms of the same element with the same number of protons, but different number of neutrons.
Ex: Carbon always has 6 protons.
Carbon 12 – 6 protons and 6 neutrons.
Carbon protons and 8 neutrons.

13. Periodic Table Mass number or atomic mass-
Equals the number of protons + neutrons.
# Neutrons = mass # - atomic number.
Atomic mass is the average mass of all isotopes in nature on the periodic table.
Because atoms are neutral, # protons = # electrons.
Atomic number = # protons = # electrons.