1. What are elements?
Element: Substance that cannot be broken down into a simpler form by ordinary chemical means.
All matter is made of elements
92 naturally occurring elements on Earth.
Elements are made up of atoms.
They Might Be Giants

2. Components of an atom
Atoms: Smallest particle of an element that has all characteristics of an element.
Nucleus: Center of the atom
Protons: “Large”, positively charged particle.
Neutrons: “Large”, neutral particle.

3. Components of an Atom Outside the nucleus:
Electrons: Negative charge found outside the nucleus in the electron cloud.
1st energy level: Can hold 2 electrons
2nd energy level: Can hold 8 electrons
3rd energy level: Can hold 18 electrons

4. There are an equal number of protons & electrons in a neutral atom
Atomic Number: Number of protons in the nucleus. This determines what element the atom is!
There are an equal number of protons & electrons in a neutral atom
*Nucleus has a positive charge*
*Atoms have neutral charge*

5. Atomic Mass: Mass of the nucleus (Number of protons + Number of neutrons)
The number of neutrons can vary in an atom, but the protons will always be equal to the atomic number.

6. Isotope Notation 8 8 Protons Electrons Neutrons Mass # Atomic #
15-8 = 7

7. How to determine Atomic and Mass #s
If you are not given the atomic number, simply look at the periodic table.
If you are not given the mass number…
If you have protons and neutrons, add them
If you don’t have protons and neutrons, take the mass from the periodic table and round to the nearest whole number

8. Sodium Br Name Symbol Atomic number Mass Number # of Protons
# of Neutrons
# of electrons
Sodium Br

9. Na 11 22.99 12 Sodium Br Name Symbol Atomic number Mass Number
# of Protons
# of Neutrons
# of electrons
Sodium Na 11
22.99 12 Br

10. Na 11 22.99 12 Br 35 79.90 45 Sodium Bromine Name Symbol Atomic number
Mass Number
# of Protons
# of Neutrons
# of electrons
Sodium Na 11
22.99 12
Bromine Br 35
79.90 45

11. Practice How many protons are there in Lithium-7?
How many neutrons are there in Lithium-7?
How many protons are there in Mg?
How many electrons are there in Mg?
How many neutrons are there in ?
How many neutrons are there in Oxygen-18?

12. Practice How many protons are there in Lithium-7? 3
How many neutrons are there in Lithium-7? 4
How many protons are there in Mg? 12
How many electrons are there in Mg? 12
How many neutrons are there in ? 11
How many neutrons are there in Oxygen-18? 10

13. Isotopes
Atoms of the same element (same # of protons), but with different numbers of neutrons.
Have different mass numbers
Isotopes behave the same chemically because they still have the same number of protons and electrons

14. Isotopes of Neon
Protons
Electrons
Neutrons 10 10 10 10 10 10 10 11 12

15. Ions So far, we have focused on neutral atoms
Which have an equal number of protons and electrons
We know the protons are tightly held in the nucleus
Held there by nuclear forces

16. Ions Electrons are scattered outside the nucleus
Less restricted and able to change
When an atom gains or loses electrons, it is called an ion

17. Gain Electrons Negative charge Called an anion Ex. Protons Electrons
Neutrons

18. Gain Electrons Negative charge Called an anion Ex. Protons 8 Electrons10
Neutrons

19. Lose Electrons Positive charge Called a cation Ex. Protons Electrons
Neutrons

20. Lose Electrons Positive charge Called a cation Ex. Protons 1310
Neutrons 14

21. Isotope (of same element)
Particle Changed
Result
Proton
Different Element
Neutron
Isotope (of same element)
Electron
Ion (of same element)

22. Normal: Atomic Mass _______
Chlorine has ________ # of protons _________ # of Neutrons _________ # of Electrons
Isotope: Atomic Mass 37
ISOTOPE) ________ # of protons _________ # of Neutrons _________ # of Electrons

23. Normal: Atomic Mass _35.45__
Chlorine has __17____ # of protons ____18___ # of Neutrons ___17____ # of Electrons
Isotope: Atomic Mass 37
___17___ # of protons ___20____ # of Neutrons ____17___ # of Electrons

24. Atom Bonding
Valence electrons: Electrons found in the outermost energy level.
Atoms bond with each other according to the number of valence electrons in order to be stable.
Stable atom=Outermost electron valence shell is full.

25. Chemical Bonds
Ionic Bonds
Covalent Bonds
Hydrogen Bonds

26. Ionic Bonds Electrons are transferred between atoms
A metal and a nonmetal
Positive & Negative Ions attract each other like magnets.

27. In a chemical formula, the positive ion is always written before the negative ion
Ex: Na+ Cl-

28. Covalent Bonds Electrons are shared between atoms Both are nonmetals
Polar molecule- shares the electrons uneqaully, giving it a + and – side.
Nonpolar molecules share equally.

29. Hydrogen Bonds Weak, intermolecular bonds
Formed when the + side of one polar molecule is attracted to the – side of another polar molecule.