1. Counting atoms and elements
Chemical Formulas
Counting atoms and elements

2. First – some vocabulary
Atom – the smallest particle of an element, that retains the chemical properties of that element
Element – the smallest unit of matter that cannot be broken down by a chemical reaction
Compound – a combination of two or more elements bonded together in some way

3. First – some vocabulary
Ions – ions are electrically charged particle, formed when an atom gains or loses one or more electrons to form a stable outer shell
Every time a chemical reaction happens, atoms gain, lose, or share electrons, causing atoms to become electrically charged

4. Charges on ions
If a Sodium atom loses its valence electrons, what will the charge on the atom be?
If a Calcium atom loses its valence electrons, what will the charge on the atom be?
If a Chlorine atom gains electrons, what will the charge on the atom be?

5. Chemical formulas
A chemical formula is a way to show the ratio of atoms in a compound
Subscript – a small number, below the line of script, representing the number of atoms of that element

6. Objective:
Determine the number of atoms of each element in chemical formulas containing subscripts

7. H2O Draw a t-chart Write the elements on the left
Element symbols start with a capital letter
Every capital letter is an element
Write the subscripts on the right

8. Practice:
SiCl4
H2SO4
Fe2O3
Na2CO3

9. If you have Parentheses:
Fe(OH)3
Al(OH)3
Al2(SO4)3
OC(NH2)2