1. Target 2-1 Tuesday, October 10, 2017
Atomic Structure
Target 2-1
Tuesday, October 10, 2017

2. Target 2-1
I can describe the structure of an atom by interpreting the periodic table.

3. Atoms Atom: smallest unit of matter There are different types of atoms
Each different type of atom is a different element

4. Atoms Most of the atom is empty space Nucleus: center of the atom
The nucleus contains almost all of the mass of the atom

5. Diagram of an Atom
Atom
Nucleus
Empty
Space

6. Subatomic Particles Subatomic = inside an atom Protons Neutrons
Positive charge (+)
Located in the nucleus
Mass of 1
Neutrons
Neutral (no charge)

7. Subatomic Particles Electrons Negative charge
Located outside the nucleus (electron cloud)
No measurable mass

8. Diagram of an Atom Nucleus Atom Electrons (in Electron Cloud)
(protons and neutrons held together by Strong Force)

9. Elements Elements are specific types of atoms
different elements = different atoms
Elements are organized on the Periodic Table

10. Elements on the Periodic Table3 Li
Lithium
6.941
Atomic Number
(whole number)
Atomic Symbol
(letters)
Element Name
Atomic Mass (decimal number)

11. Atomic Number
Atomic Number: tells us the number of protons in an atom of that element
Same for every atom of an element
Same number of protons and electrons (overall charge of atom is 0)
Ex) 2+ and 2- = 0

12. Mass Number Mass Number: the total mass of an atom
Mass number = # of protons + # of neutrons # of neutrons = Mass Number – # of protons
Electrons are not counted in the mass number
Two ways to write mass numbers: lithium Li both mean an atom of lithium (Li) with a mass of 7 7

13. Isotopes
Mass number is NOT always the same for every atom of an element
Isotopes are atoms of the same element that have different mass numbers
Happens because of different # of neutrons
Ex) Lithium-7 and Lithium p, 4n p, 3n

14. Atomic Mass
Atomic Mass: is the average mass number of all the isotopes of an element
The atomic mass is always a decimal because it’s a calculated average
If you are not given a mass number, you can estimate it by rounding the atomic mass to the nearest whole number

15. Exit Ticket
How many p, e, n are there in…
Magnesium-25
Fluorine-20
Beryllium