Transcript Elements in the same group have what in common?

Elements in the same group have what
in common?
Agenda for Tuesday Jan 4th
1. Reactivity Lab
What is the difference between an
element and compound?
Agenda for Wednesday Jan 5th
1. Compounds/molecules
2. Ions
Formulas
• Elements and Symbols
– Sodium = Na
– Carbon = C
• Formulas – shows how many atoms of each
element is in a substance
– H2O
– 5 CO2
Formula Weight
• Total weight for a molecule
– Add the atomic weights of all atoms in the molecule
together
H2 O
H = 1.0079 *There are 2 H’s so we multiply by 2
O = 15.99994
5 CO2
What is the total weight for 2 NO2?
Agenda for Thursday Jan 6th
1. Ions and charges
Charge on an atom
• Atoms have a neutral charge
• Why?
– The number of electrons (negative charges) cancel
out the number of protons (positive charges)
Ions
• Ion – an atom that loses OR gains electron(s)
• A Cation is an atom that has lost an electron
– positive (+) charge
• An Anion is an atom that has gained an
electron
– negative (-) charge
Ions
• If Sodium loses an electron what is its charge?
– Lose a negative = positive
• If Chlorine gains an electron what is its charge?
• How do we know which atoms will lose and
gain electrons?
Charges on atoms
• Use the periodic table to predict charge on an atom
• Oxidation Numbers - charges
+1
+2
+3
+4 -3 -2 -1
Practice Oxidation Numbers
K
Ca
Mg
Cl
P
N
B
O
Li
Na
C
Al
F
Ne
Br
S
Si
H
Be
I
Charges
MgCl2
What is the charge of the Magnesium atom?
What is the charge of the Chlorine atoms?
Find the charges of each atom and the overall
charge for : Na2S
The overall charge always equals 0!!
Practice Zero Net Charge
How many of each atom do you need to balance
(create a zero net charge)?
• Na+ and Cl• K+ and N3• Li+ and S 2• K+ and O 2• K+ and C 4• S 2- and B 3+
Find the charge of each atom and
the overall charge of KCl
Agenda for Friday Jan 7th
1. Quiz
2. Finish activity
3. Ionic and covalent compounds