2. smallest unit of an element that retains the properties of that element.

3. (+) positive charge
Inside Nucleus
1 amu*
Inside Nucleus
no charge
1 amu*
(-) negative charge
no mass
(≈ zero)
Outside Nucleus
*amu (atomic mass unit)

4. amu (atomic mass unit): the mass of something as small as a proton, (1
amu (atomic mass unit): the mass of something as small as a proton, (1.67 x g), is not a very convenient number to work with. So, scientist came up with a relative atomic mass system that would make these measurements easier to use.
It was arbitrarily decided that the carbon-12 atom would be the standard for comparison for all other atoms. The masses of all other atoms are expressed in comparison to the carbon-12 atom.
One amu is equal to 1/12 the mass of the carbon-12 atom. Since carbon-12 has 6 protons and 6 neutrons, the amu for one proton or neutron is equal to 1 amu.
amu (atomic mass unit) = 1/12 the mass of carbon-12
1 proton = 1 amu
1 neutron = 1 amu
1 electron = 0 amu

5. p+ +1 1
1.67 x 10-24 n0 1
1.67 x 10-24 e- -1
1/1840
9.11 x 10-28

6. The Nucleus Protons & Neutrons Electron Cloud Positively Charged
Almost All of the Mass of the Atom
Electron Cloud
Where the Electrons are Found
Almost All of the Volume of the Atom

7. Protons Neutrons Electrons
Positive
Charge No
Charge
Negative
Charge
Most of the atom’s Mass.
Most of the atom’s Volume.

8. Quarks and Leptons: Quarks
they are seen as the "elementary particles” of matter
In the present standard model, there are six "flavors" (types) of quarks and leptons.
Quarks
make up protons & neutrons
6 “flavors” (types)
3 quarks = 1 proton or 1 neutron
gluons:
Neutrons:
2 downs & 1 up quarks
Protons:
2 ups & 1 down quarks
Electrons are Leptons
QUARKS

9. Atoms are incredibly small.
Atoms are measured in picometers (pm)
— 1 pm = m
— Hydrogen, the smallest atom, measures only a 32 pm radius
Nucleus- very small compared to the whole atom
Density of the nucleus 1014 g/cm3
(2 x 108 metric tons/cm3!)
If the atom was the size of an NFL stadium…
the nucleus would be the size of a marble on the fifty yard line…
…and the electron cloud would be the rest of the stadium for the electrons to run around in.

10. Atomic number is represented by Z
Atomic Number = number of protons
# of protons determines kind of atom
(determines the element!)
Atomic Number = number of electrons
in a neutral atom!
Mass Number = sum of protons + neutrons
Atomic number is represented by Z
Z = #p+

11. What’s the difference between these two carbon nuclei
Atomic Number = number of protons
# of protons determines kind of atom
(determines the element!)
Atomic Number = number of electrons
in a neutral atom!
Mass Number = sum of protons + neutrons
Mass Number
What’s the difference between these two carbon nuclei
Atomic Number

12. (if it’s a neutral atom!)
Mass Number
# p+ + # n0 = mass #
Atomic Number
12(mass #)
- 6 (# p+)At.#
6 (# n0)
Atomic # = # p+ & # e-
(if it’s a neutral atom!)

13. Hyphen notation-
the mass number is written with a hyphen after the element name- (spelled out- not symbol)
copper-65
Nuclear symbol-
the subscript = atomic #
the superscript = mass #

14. Atomic #29 = 29 p+ & 29 e-
Mass # = p+ + n0
So, Mass # - p+ = n0
65 – 29 p+ = 36 n0

15. = 3
= 7 +
= 3
= 4
= 3

16. = 27
= 59
= 27
= 32
= 27

17. = 53
= 127
= 53
= 74
= 53

18. = 21
= 24
= 21

19. = 63
= 152
= 63
Europium-152

20. = 78
= 195
= 78
Platinum

21. Cu Copper 29 Atomic Number Element Name 63.546 Element Symbol
Average Atomic Mass

22. Copper Cu
63.546 29

23. Mg 24 12 12 12 12 Br
79.904 80 35 35 45 35 Cd
112 48 48 64 48 Mg 12 Br
79.904 35 Cd 48

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