1. The Atom Chm 1.1.1

2. Essential Standards Chm 1.1.1 Characterize the protons, neutrons, electrons by location, relative charge, relative mass (p=1, n=1, e=1/2000.) Use symbols A=mass number, Z=atomic number

3. What is an atom? The smallest particle of an element that retains its identity in a chemical reaction

4. Sizing up the atom Read pg. 103 silently

5. Subatomic particle 3 kinds of subatomic particles Electrons, protons, and neutrons

6. electrons Negatively charges subatomic particles e-

7. protons Positively charged

8. neutrons No charge or neutral

9. nucleus Each atom contains a nucleus Inside the nucleus are protons and neutrons Outside the nucleus is electrons

10. Chart See chart pg. 106 Please copy in notes-change 1840 to 2000 Which subatomic particle is the smallest?

11. Mass number and atomic number Elements are different because they contain different numbers of protons The atomic number is the number of protons in the nucleus in the atom in that element The symbol for atomic number is Z The atomic number identifies the element and can be found on the periodic table

12. Atomic number Ex. Atomic number or Z for Oxygen=8 Sulfur, Z=16 Hydrogen, Z=1 You try… Boron (B), Z=? Chlorine (Cl), Z=?

13. Mass number The total number of protons + neutrons in an atom See table on page 110 Add the number of protons and neutrons and see if that equals the mass number

14. Mass number Can be found on periodic table mass number or A of Hydrogen (H)=1.00794 Sulfur (S), A=32.066 Chlorine (Cl), A=35.453 You try… Lithium (Li), A=? Sodium (Na), A=?

15. Mass number The number of neutrons in an atom is the difference between the mass number and atomic number Number of neutrons= mass # - atomic # Let’s try oxygen Neutrons = 16-8 Neutrons=8

16. Mass number Number of neutrons= mass # - atomic # How many neutrons does Chlorine (Cl)have?

17. notation The composition of any atom can be represented in shorthand notation using atomic # and mass # The chemical symbol Au appears with 2 numbers written to its left The atomic number is subscript The mass number is superscript Ex. 197/79 Au=Gold or gold-197

18. Try it out Practice pg 112