1. IOns
Charged Atoms

2. Why would an atom lose or gain electrons???
Neutral atoms ‘want’ their electrons to be in a stable configuration
Usually means that the outermost shell is full of e’s
The Nobel Gases (last column on the right) naturally have a full outer shell and are therefore stable
Elements try to get the same number of electrons as the closest Nobel Gas
Gain to look like the NEXT one
Lose to look like the PREVIOUS one
Depends on the which option needs the least amount of energy (ionization energy)

3. When an atom forms an ion
The ion is physically different from the original atom
Anions are larger than their parent atoms
Cations are smaller than their parent atoms
The ion is chemically different from the original atom
Examples:
Fluorine atom is the most reactive element (can even dissolve glass). Fluoride ion is much less reactive and essential to dental health.
Cells require sodium and potassium ions for proper function. Sodium and potassium atoms are harmful to cells – react violently with water!

4. HOW does an atom carry a negative charge?
To form a negatively charged ion
An atom would need to GAIN electrons to fill its outer shell (and LOOK stable – like a noble gas)
Called an ANION
For example: Chloride ion
Formed when the Chlorine atom(17 p’s & 17 e’s) GAINS an additional electron (17 p’s &18 e’s) 
17 +
17 -
e- +
18 -
NOTE: the # of protons DIDN’T change!

5. HOW does an atom carry a negative charge?
Notice:
ANIONS have a different name then their parent atom
The ending is removed and –ide is added
Fluorine 
Oxygen 
You MUST know
Non-metals tend to form anions
oxygen family will form anions with a 2- charge (O2-, S2-, etc.)
halogen family will form anions with a 1- charge (F-, I-, etc.)
the superscript tells you the charge of the ion
Fluoride
Oxide

7. Learning Check 2- Oxygen family 1- 3 electrons Sulfide
If an atom with 16 protons GAINS 2 electrons, what will it’s new charge be?
What family does this atom belong to?
What charge will any member of the halogen family carry?
How many e’s does an atom with a 3- charge gain?
What is the name of the ion formed from sulfur?
How does it form? 2-
Oxygen family 1-
3 electrons
Sulfide
By GAINING 2 electrons

8. HOW does an atom carry a positive charge?
To form a positively charged ion
An atom would need to LOSE electrons, losing its outer shell (the atom’s inner shell is full so it will LOOK stable)
Called an CATION
For example: Magnesium ion
Formed when the Magnesium atom (12 p’s & 12 e’s) loses 2 electrons (12 p’s &10 e’s)
12 +
12 - 
10 -
+ 2 e‑
NOTE: the # of protons DIDN’T change!

9. HOW does an atom carry a positive charge?
Notice:
CATIONS have the same name as their parent atoms
You MUST know
Metals tend to form cations
alkali metals will form cations with a 1+ charge (Li+, Rb+, etc.)
alkaline earth metals will form cations with a 2+ charge (Be2+, Ca2+, etc.)
the superscript tells you the charge of the ion
Transition metals can form different cations
For example, Iron can form Fe2+ or Fe3+ - depends on what it is doing with its electrons to look stable

11. Learning Check 1+ Alkali metals 2+ 3 electrons Calcium
If an atom with 19 protons LOSES 1 electron, what will it’s new charge be?
What family does this atom belong to?
What charge will any member of the alkaline earth metals family carry?
How many e’s does an atom with a 3+ charge lose?
What is the name of the ion formed from calcium atom?
How does it form? 1+
Alkali metals 2+
3 electrons
Calcium
By LOSING 2 electrons

12. Very Special Ions POLYATOMIC IONS First Quiz – Mon/Tues Sept 19/20!
There is a very special group of ions known as
POLYATOMIC IONS
charged entities composed of several atoms bound together that stay together when forming larger compounds
You MUST know 22 of the most common polyatomic ions (their formula, including charge & name) and be able to recognize them in formulas!
First Quiz – Mon/Tues Sept 19/20!

13. Formula Name C2H3O2- Acetate HPO42- ClO- Hypochlorite HSO4-
Hydrogen phosphate
ClO-
Hypochlorite
HSO4-
Hydrogen sulfate
ClO2-
Chlorite
MnO4-
Permanganate
ClO3-
Chlorate
NH4+
Ammonium
ClO4-
Perchlorate
NO2-
Nitrite
CN-
Cyanide
NO3-
Nitrate
CO32-
Carbonate
O22-
Peroxide
Cr2O72-
Dichromate
OH-
Hydroxide
CrO42-
Chromate
PO43-
Phosphate
H2PO4-
Dihydrogen phosphate
SO32-
Sulfite
HCO3-
Hydrogen carbonate
SO42-
Sulfate