1. 1

2. Vocabulary
ATOM-the smallest unit that maintains the characteristics of an element
Nucleus- The center of the atom, contains protons and neutrons
Electron Cloud –Region surrounding the nucleus containing the electrons 2

4. The Atom 4

5. The Atom 5

6. Nucleus
Protons
Neutrons 6

7. The Nucleus
Proton-A positively charged sub-atomic particle (+). Atomic Mass=1 amu
The number of protons is the same as the atomic number Li 3 7
The Atomic Symbol
The atomic mass
The atomic mass 7

8. Li 3 7 The Nucleus Neutrons –A sub-atomic particle in the nucleus
--Has a mass equal to 1 atomic mass unit
--Neutron do not have a charge (0)
To calculate the number of neutrons in an element… Li 3 7
The atomic number
The atomic mass
The atomic number
The number of neutrons
The atomic mass
The atomic mass 8

9. Li 3 7 7 (Atomic Mass) 3 protons(Atomic #) 4 neutrons
The atomic number
The atomic mass
The atomic mass 9

10. WRITING RESPONSE How many protons does Mg have?
How many neutrons does Mg Have?

11. WRITING RESPONSE How many protons does Mg have?12
How many neutrons does Mg Have? 12

13. The Atom 13

14. The Electron Cloud Electrons- Valence Electrons
The number of electrons equals the number of protons
Sub-atomic particle with a negative charge (-)
Electrons behave as if in a 3-D orbit
Valence Electrons
The outer most electrons
Valence electrons are responsible for bonding 14

15. WRITING RESPONSE How many protons? How many neutrons?
How many electrons?

16. WRITING RESPONSE How many protons? 3 How many neutrons? 4
How many electrons? 3

18. Bohr Model The first shell can have 2 electrons The second shell can18

19. Shells and the Electron Cloud19

20. Let’s look at a few elements…
Hydrogen
1= Proton 1= electron 20

21. Let’s look at a few elements…
Helium
2=protons 2=neutrons 2=electrons 21

22. Let’s look at a few elements…
Lithium
3=protons 4=neutrons 3=electrons 22

23. Let’s look at a few elements…
9=protons 10=neutrons 9=electrons
Fluorine 23

24. Let’s look at a few elements…
18=protons 22=neutrons 18=electrons
Argon 24

25. ISOTOPES
Atoms that have the same # of protons but have neutrons that have been added, resulting in a different atomic mass.

27. IONS
Charged particles that occur when an atom gains or loses an electron during chemical bonding.
If the atom gains an electron- Negative charge
Ex: Cl-
Most non-metals form negative Ions
If the atom loses an electron- Positive Charge
Ex: Na+
Most metals form Positive Ions

28. Losing an Electron = Positive ion
Na+ has 11 protons but only 10 electrons
Gaining an Electron = Negative ion
Cl- has 17 protons but has 18 electrons

29. What would the charge be on an atom that lost an electron
What would the charge be on an atom that lost an electron? Gained two electrons?

30. Which shows a negative ion? Explain
Which shows a neutral atom? Explain
Which shows a positive atom? Explain B C