1. The Atom & The Periodic Chart
Basic Chemistry
The Atom
&
The Periodic Chart

2. Atom Fundamental organizational unit of matter
Made up of smaller components
Have a neutral charge

3. Atomic Structure Neutron: neutral charge Electron: - charge
Proton: + charge
Neutron: neutral charge
Electron: - charge

4. The Periodic Chart Chemical Symbol: abbreviated name of an element
1st letter always capital
2nd letter always lowercase
Atomic Number: the number of protons in the nucleus of an atom
# protons = # electrons because atoms are neutral
the periodic chart is arranged by increasing atomic number
Mass Number: the number of protons + the number of neutrons
the mass of the atom
1 proton = 1 amu
1 neutron = 1amu
the mass of the electron is so small it is ignored

5. 1
Atomic Number
Chemical Symbol
Mass Number H
1.0079

6. Isotopes
atoms with the same number of protons but a different # of neutrons
number of neutrons changes the mass but not the charge
this is the reason that the mass number is not a whole number

7. Isotope Examples Carbon -12 Carbon-14 6 protons and 6 neutrons 6+6=12
6+8= 14

8. Period: a row of elements on the periodic chart
= number of energy levels
Group: a column of elements on the periodic chart
have similar characteristics
= number of valence (or outer) electrons

9. The Electrons
Energy Levels: the route around the nucleus of an atom that an electron travels
the bigger the orbit the more energy in the electron
Orbitals: places within an energy level where electron tends to be found
it is impossible to pinpoint exactly where an electron is located
Valence Electrons: electrons in the outermost orbital
determine properties of the element

10. Orbitals s p d f 1 2 x 8 6 3 18 10 4 32 14 5 7 Energy Level
Number of Electrons s p d f 1 2 x 8 6 3 18 10 4 32 14 5 7

11. s p d f

12. Write an electron configuration for Aluminum.
1s2
2p6
2s2
3s2
3p1

13. Al 1s2 2s2 2p6 3s2 3p1 The energy levels The orbital
The number of electrons
The outermost energy level
(this level houses the valence electrons)
The valence electrons

14. A New Twist on Electron Configurations
The d and f orbitals lag behind

15. Uuo
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f14 6d10 7p6
Key
Lagging 1 Level Behind
Lagging 2 levels Behind

16. Another Twist

17. Stability
Full Energy Level
Full Sublevels
Half Full Sublevels

18. Expect: [Ar] 4s2 3d9
Actually: [Ar] 4s1 3d10 Fill the lower level to increase stability
Copper

19. chromium Expect: [Ar] 4s2 3d4
Actually: [Ar] 4s1 3d5 Half fill the lower level to increase stability
chromium

22. Electronegativity: the higher the electronegativity the greater the ability to pull electron to itself

23. Atomic Size: the more energy levels the larger the atom the more electrons in the levels the greater their attraction to the nucleus (electrostatic attraction)