1. Atoms and Molecules

2. Atoms
Atoms are basic building blocks of matter that make up everyday objects.

3. Atoms
Protons
Neutrons
Electrons

4. Electrons Electrons orbit around an atom. They have a negative charge.
They are lighter than protons or neutrons.

5. Protons They are positively charged. Are located in the nucleus.
Provide most of the atomic mass, along with neutrons

6. Neutrons Neutrons are neither positive nor negative.
Also in the nucleus

7. Elements
An element is a substance made up of only one kind of atom.

8. Molecules
A molecule is a group of two or more atoms held together with a bond
                  

9. Compounds
A compound is two or more elements combined together.

10. cation – ion with a positive charge
An ion is an atom, or group of atoms, that has a net positive or negative charge.
cation – ion with a positive charge
If a neutral atom loses one or more electrons
it becomes a cation. Na
11 protons
11 electrons
Na+
11 protons
10 electrons
anion – ion with a negative charge
If a neutral atom gains one or more electrons
it becomes an anion.
Cl-
17 protons
18 electrons Cl
17 protons
17 electrons
2.5

11. A monatomic ion contains only one atom
Na+, Cl-, Ca2+, O2-, Al3+, N3-
A polyatomic ion contains more than one atom
OH-, CN-, NH4+, NO3-
2.5

12. Ions Ions are written with their charge included
If Aluminum loses three electrons, it will be: Al+3
If Chromium gains an electron, it will be: Cr-1

13. The ionic compound NaCl
ionic compounds consist of a combination of cations and an anions
the sum of the charges on the cation(s) and anion(s) in each formula unit must equal zero
Often a metal + nonmetal
The ionic compound NaCl
2.6

14. Molecular compounds nonmetals or nonmetals + metalloids common names
H2O, NH3, CH4, C60
element further left in periodic table is 1st
element closest to bottom of group is 1st

15. Why do ionic bonds lose electrons?
Electrons exist in “shells” around the nucleus
Every atom wants their outermost shell to be full
Atoms will gain or lose electrons to make this possible
Examples: Sodium, Potassium, Chlorine

16. Full Shells
The desire for a full outer shell, or “valence shell” leads atoms to bond with each other in various ways

17. Chemical Bonds
Chemical Bonds are the attractive force that holds atoms or ions together
- 3 types
ionic, covalent, metallic

18. Ionic Bonds
- Bond formed by the attraction between oppositely charged ions
- oppositely charged ions attract each other and form an ionic bond
ex. Na+ + Cl- = NaCl

19. Ionic Compounds Multiple ion bonds together forms an ionic compound
The strong attraction between ions creates a rigid framework, or a crystal lattice

20. Covalent Bonds
- Chemical bond in which two atoms share a pair of valence electrons
- Can be a single, double, or triple bond
- Always formed between nonmetals

21. Covalent Bond Cont. Non Polar - bonded atoms that share e-’s equally
- same atoms bonded
ex. Cl – Cl: Cl2
Polar
- bonded atoms that do not share e-’s equally
- different atoms bonded
ex: H H O

22. Brief Review Interlude
Electron shells:
Atoms have “shells” of electrons spinning around them
These electrons can exist only in certain numbers in each shell

23. Groups Group 8 = 8 electrons Group 1 = 1 electron
Each column is called a “group”
Group 2 = 2 electrons
3, 4, 5, 6, 7
Each element in a group has the same number of electrons in their outer orbital, also known as “shells”.
The electrons in the outer shell are called “valence electrons”

24. Transition metals can have anywhere between 2 and 7 valence electrons

25. Full Shells
The desire for a full outer shell, or “valence shell” leads atoms to bond with each other in various ways

26. So?
Bellwork: Why are electrons the most important part of a chemical reaction?

27. Activity
Figure out the valence electrons of your atom(s). Write that number down.
Also: Look in your notes/research. Does it say if your element is more likely to be ionic or covalent?