1. Unit 2: Structure of atoms and ions

2. What makes up an atom?
Nucleus (protons and neutrons) and electrons

3. Protons, electrons, and neutrons
Charge
Relative mass
Proton
Positive (+) 1
Neutron
Neutral (no charge)
Electron
Negative (-)
1/2000

4. Neutral Atoms
In neutral atoms (no charge), electrons (-) and protons (+) are equal
Why?
(+)2 + (-)2 = 0
(+)2 + (-)1 = +1
No charge (neutral)
Positive charge

5. Protons, electrons, and neutrons
Atomic number = # of protons
If atom is neutral, it is the number of electrons too.
Mass number

6. Protons, electrons, and neutrons
Mass number = # protons + # neutrons
Mass number

7. Warm-up Why do some atoms have charges while others are neutral?
Name one element that has a different number of protons and neutrons.
What would be the charge of Zinc if it had 28 electrons?
What is the relative mass of protons, neutrons, and electrons?

8. Ions Ions are charged atoms Cations = positively (+) charged atoms
Anions = negatively (-) charged atoms

9. Don’t Fall! Element Mass # of Protons # of Neutrons # of Electrons K
79.9 g/mol 35
Al+3 13
39.1 g/mol 19 20 19 Br 45 35
26.98 g/mol 14 10

10. Homework Element Mass # of Protons # of Neutrons # of Electrons N
30.97 g/mol 15
Na+1 11
O-2 17 18

11. Isotopes
Same number of protons (and electrons), but different number of neutrons
Isotopes are often unstable and radioactive!
After first bullet: What would this affect mass number or atomic number?
Same # protons

12. Summary Atom Neutral atom Same # of protons and electrons Ion
Different # of protons and electrons
Isotope
Different # of protons and neutrons

13. How are electrons configured around the nucleus?

14. Electron Configuration
Level
State
Neighborhood
Sublevel
Block
Neighborhood
House
Orbital
House
Electrons
People
People

15. Levels There are 7 levels (neighborhoods)
Each level is higher in energy and less stable. 1 1 2 3 4 5 6 7

16. Sublevels
Each level (neighborhood) can have up to 4 sublevels (blocks)

17. Orbitals and Electrons
Orbitals (houses) are where the electrons (people) are housed within a sublevel (block).

18. Mapping Electrons
Electron Configuration is a way to map the location of electrons for an element.
Mapping occurs from left to right, moving down the Periodic Table.

19. Electron Configuration
Electron Configuration for Oxygen 1s 2 1 2s 2 1 4 3 2 1 2p

20. Checking Electron Configuration
How many electrons does Oxygen have?
Oxygen -1s22s22p4
2+2+4=8

21. Bohr Models A basic model of the atom.
Protons, neutrons, and electrons
Energy levels

22. How to Draw a Bohr Model Draw the nucleus.
Write the # of protons and neutrons in the nucleus.
Draw the electrons evenly distributing them throughout each level.
Follow rules for # of electrons for each level.

23. Rules for Energy Levels
Level 1 (closest to the nucleus) can hold a maximum of 2e.
Level 2 can hold a max of 8e.
Level 3 can hold a max of 18e.
Level 4 can hold a max of 32e.
You must fill one level before going on to draw the next level!

24. How to Draw a Bohr Model
Bohr Model for Oxygen
8 p
8 n

25. Valence Electrons
The highest energy level contains the valence electrons.
Valence electrons participate in bond formation.
Atoms are most stable when they have 8 valence electrons.

26. Valence Electrons 6 How many valence electrons does Oxygen have? 8 p

27. Valence Electrons +1 1 +2 +3 ±4 -3 -2 -1 8 2 3 4 5 6 7

28. Lewis Dot Diagrams Lewis Dot Diagrams shows only valence electrons.
How to:
Write the element symbol
Determine the number of valence electrons
Draw valence electrons around each side of the symbol.

29. Energy Exists in discrete units called quanta.
Energy is a result of electrons moving.
Electrons like to be close to protons (nucleus)

30. Gaining Energy
Further from nucleus = higher energy

31. Losing Energy
Closer to nucleus = lower energy

32. Losing Energy Produces electromagnetic radiation called photons.

33. Losing Energy
This loss in energy emits electromagnetic radiation called photons.
Photon=a packet of energy
Responsible for visible light.

34. Wavelength
Wavelength and frequency are inversely proportional.

35. Electromagnetic Spectrum