1. CST Review Day 1 “Must we do it? I don’t want to do it!”

2. Objectives 1.Atoms consist of protons, electrons, and neutrons. 2.Elements are identified by their atomic numbers in the PT. 3.Mass Numbers of some elements can differ because of isotopes.

3. Atoms… Consist mostly of empty space. Consist of three sub- atomic particles: protons, electrons, and neutrons. Has a central region called the nucleus where most of the mass of the atom is concentrated. Nucleus

4. THE SUB-ATOMIC PARTICLES ParticleLocationCharge Protons = p + Inside the nucleus Positive Neutrons = n o Inside the nucleus No Charge Electrons = e - Outside the nucleus; inside electron clouds. Negative

5. Number of p + = Number of e - An ATOM carries NO charge. This is because the number of positive charges equal the number of negative charges. The number of PROTONS can NEVER change. That means an ELEMENT will always have the same number of protons.

6. Checkpoint:Checkpoint: 1.What do we call the central region of the atom? 2.Which two particles are found inside this region? 3.Where can electrons be found? 4.What is the over-all charge of the atom? 5.Can the number of protons in an atom change?

7. 2. This central region is the _____________. It contains two particles: ___________ and ___________. 1.This particle is most probably the ______, which has a ________ charge.

8. The Periodic Table lists all elements according to their atomic numbers, which is the number of protons it has. The atomic number of VANADIUM is 23.

9. 1.How many protons does IRON have? 2.How many electrons does IRON have? 3.What is the atomic number of the element next to Iron in the PT?

10. A.Which element is this? B.What is its atomic number? C.How many electrons should it have? Should this element be found right beside the element on the left? Why or Why not?

11. MASS NUMBER! The MASS NUMBER describes how “heavy” an element or atom is. It is the total number of protons plus neutrons in the nucleus. This is the collectively the MASS NUMBER! 35 amu

12. ISOTOPES… The number of NEUTRONS can change, this means the mass of the element can be different for different