1. Unit 4: Splitting & Unstable Matter: Atoms & Nuclear Chemistry
Please turn on your speakers. There is sound added to this PowerPoint.
Unit 4: Splitting & Unstable Matter: Atoms & Nuclear Chemistry
Subatomic Particles

2. 3 Types of Subatomic Particles
atom  the smallest particle of an element that has all of the properties of that element
3 Types of Subatomic Particles
Subatomic Particle
Symbol
Location in the Atom
Charge
Mass (g)
Relative Mass (amu)
Special Role
 Proton p+
Inside nucleus
1+ 
1.673 x 10-24  1
Determine the identity of the element
 Neutron no
1.675 x 10-24 1
Utilized in nuclear reactions
Electron
 e-
Outside nucleus 1-
9.109 x 10-28
1/1836
Determine the chemical behavior of the element

3. Atomic Mass Unit (amu)  special unit for measuring the mass of an atom; amu = 1.66 x g; equal to 1/12th of the mass of a carbon atom
LEARNING CHECK:
What charge does the nucleus have? Justify your answer.
The nucleus has a positive charge because the nucleus contains protons and neutrons. Protons are positive and neutrons are neutral so the charge is positive.

4. LEARNING CHECK:
Where is most of the mass of the atom found? Justify your answer.
Most of the mass of the atom is found in the nucleus because it contains the two heaviest subatomic particles (neutrons and protons).
LEARNING CHECK:
Why do you think it is important to have a special unit (amu) to measure the mass of an atom?
The mass of an atom is so small that we need a special unit that represents a very small number.

5. nucleus positively charged and very dense center of the atom that contains the protons and neutrons
electron cloud  area surrounding the nucleus that contains the electrons and occupies (takes up) most of the volume (space) of the atom

6. Just how small is the nucleus?
If an atom were the size of a football stadium, then its nucleus would be about the size of a marble!

7. Just how small is an atom?
If 100,000,000 copper atoms were placed side by side, they would form a line 1 cm long. What is this number of atoms written in scientific notation?
1 x 108 atoms

8. LEARNING CHECK:
What makes up most of the atom? Justify your answer.
Empty space because most of the volume of an atom is the electron cloud. Electrons have very little mass.

9. LEARNING CHECK:
Label the nucleus, electron cloud, electrons, protons, and neutrons on the atom to the right.
neutrons
electrons
protons
nucleus
Electrons cloud

10. APE (Atomic Number = # of Protons = # of Electrons)
atomic number  the number of protons in the nucleus of an atom; (NOTE: ON THE PERIODIC TABLE!)
APE (Atomic Number = # of Protons = # of Electrons)
Why is APE true?
A neutral atom (an atom with no charge) must have the same amount of positive charge and negative charge. Therefore, the protons must equal the electrons.

11. LEARNING CHECK:
Determine the number of protons and electrons from each of the following elements.
Element
Number of Protons
Number of Electrons
Calcium
Aluminum
Rhodium 20 20 13 13 45 45

12. MAN (Mass Number = Atomic Number + # of Neutrons)
mass number  is equal to the total number of protons plus neutrons in the nucleus of an atom (NOTE: NOT GIVEN ON THE PERIODIC TABLE!)
MAN (Mass Number = Atomic Number + # of Neutrons)
LEARNING TARGET:
Why are electrons not included when calculating the mass number?
Electrons are WAY lighter than a proton or neutron so we can assume that their mass does not affect the mass number.

13. LEARNING TARGET:
Complete the following table.
Element
Number of Protons
Number of Neutrons
Mass Number
Carbon 12
Sodium 22
Bromine 45 6 6 11 11 35 80

14. 2 Ways to Indicate Mass Number
Hyphen Notation
Nuclear Symbol
 Chlorine - 35
Cl 
Mass number 35 17
Atomic number

15. LEARNING CHECK: Write the hyphen notation and nuclear symbol for the element containing 4 protons and 5 neutrons.
Hyphen Notation
Nuclear Symbol
 Beryllium - 9
Br 
Mass number 9 4
Atomic number