1. Structure of an Atom

2. Atoms Smallest particle of matter
All atoms of the same element are basically the same
atoms of different elements are always different

3. Parts of Atom Nucleus Center of an atom 2 parts: Protons Neutrons
Positive charge
Mass= 1 amu
Neutrons
Neutral- no charge

4. Electron Negative charge Located outside nucleus
Always in motion some distance from nucleus in the electron cloud
Mass is very small in relation to the mass of the proton or neutron (so it is negligible in calculating the mass of an atom)

5. Practice Problem 1
What is the net charge on a particle that consists of 15 protons, 16 neutrons and 18 electrons? -3

6. Practice Problem 2
What is the net charge of a particle that contains 10 protons, 9 neutrons and 8 electrons? +2

7. Practice Problem 3
What is the net charge of a particle that contains 1 proton, 0 neutrons and 1 electron? 0

8. Practice Problem 4
Where is most of the mass located in the atom? In nucleus

9. Practice Problem 5
If an atom has 9 protons and 10 neutrons, how many electrons must it have? 9 electrons

10. Complete Structure of Atom Review Worksheet

11. Atomic number = Number of protons
Each atomic number is specific to a certain element
No two different elements have the same atomic number or number of protons
Periodic table is set up in order of increasing atomic number

12. Practice Questions How many protons are in oxygen?8
Potassium (K) has how many protons? 19
Which has more protons, Lithium (Li) or Sodium (Na)? Na

13. If you are talking about a particular element, the number of protons will never change even if the charge changes.
If this is the case, what must change in order for the charge to change?
Number of electrons

14. If atom is neutral, # protons = # electrons
How many electrons are in a neutral atom of Carbon? 6
If an atom is neutral and contains 1 proton, what element is it?
Hydrogen (H)
How many electrons are in a neutral atom of Zinc? 30

15. All atoms of an element are not necessarily identical
They have same physical and chemical properties
can have different numbers of neutrons
This causes atoms to have different masses
Atoms of the same element with different masses are called isotopes.

16. Isotopes Always have the same number of protons
Have same atomic number
Different numbers of neutrons
Different masses (mass numbers)
mass of atom = number protons + number of neutrons
Isotope symbol

17. What do you know about this isotope?

18. Ions Charged element Positive ions: # protons > # electrons
Negative ions: # protons < # electrons

19. Another Isotope symbol
C - 13 Symbol – mass number