ChemCatalyst
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Transcript of ChemCatalyst
ChemCatalyst How would you make an aluminum ion
from an aluminum atom? What type of ion is this?
How would you make an oxide ion from an oxygen atom? What type of ion is this?
ChemCatalyst How would you make an aluminum ion from
an aluminum atom? What type of ion is this? Al+3 so remove 3 electrons Cation
How would you make an oxide ion from an oxygen atom? What type of ion is this? O-2 so add 2 electrons Anion
(Ion)derstand Ions
Ions Atoms are neutral
Equal number of protons and electrons
Atoms can become charged by gaining or losing an electron Called ions
Ions are indicated with a (+) or (-) sign Cations are positive Anions are negative
Why Gain or Lose?
Noble gases are unreactive
Most stable elements
Atoms of elements gain or lose electrons to become more like noble gases
Cations and Anions
Two Types of Cations and Anions
Monatomic Ions Ions containing one type of atom
• Ca2+ O2-
Polyatomic Ions Ions containing two or more types of
atoms
• NH41+ NO3
1-
Metals (left side of table)
Form cations
Lose electrons to get to the noble gases
Only works if the charge is +3 or less
Cation Formation
Na Na+e-
Naming Metal Cations Metal name + “ion”
For transition metals use systematic name
Metal name followed by charge written as a Roman numeral in paranthesis + “ion”
Naming Metal Cations Example
Write the systematic name for Fe+2 and Fe+3.
• Fe+2
• Iron(II) ion
• Fe+3
• Iron(III) ion
Nonmetals (right side of table)
Form anions
Gain electrons to get to the noble gases
Only works if the charge is -3 or less
Anion Formation
Cl-e-Cl
Naming Nonmetal Anions Nonmetal root ending in “ide” + “ion”
Example What is the name of the hydrogen
anion?• Hydride ion
What is the name of the nitrogen anion?• Nitride ion
Making Salt What is the formula for table salt?
What does Na need to do to become like a noble gas?
• Lose an electron
What does Cl need to do to become like a noble gas?
Gain an electron
Making Salt
But Why?! Ions form so each atom can become
like a noble gas When the cation and anion form, we get
two charged ions
Opposite charges attract Electrostatic force Ionic bond = Ionic compound
Metal + nonmetal Left side + right side
Trends in the Table Alkali Metals
Form +1 ions
Alkaline Earth Metals Form +2 ions
Transition Metals Can have multiple charges
Halogens Form -1 ions
Noble Gases Do not form ions
Chemical Formulas
Set of symbols that represent a compound Contains two or more elements chemically
combined
How does a chemical formula differ from a chemical symbol? Formula is for a substance containing
several elements Symbol is for a single element
Symbols vs. Formulas
What do Na and O represent? The chemical symbols for sodium and
oxygen What does Na2O represent?
The chemical formula for sodium oxide What does the 2 stand for?
• 2 sodium ions
Why do we put subscripts? To count atoms/balance charges
Naming Formulas
Ionic compounds What is the name of AlBr3?
• No transition metal Step 1: Write the cation name
• Cation is Al+3 = aluminum ion Step 2: Write the anion name with the
ending –ide• Anion is Br- = bromide
Aluminum bromide
Naming Formulas
Ionic compounds What is the name of NiS?
• Nickel is a transition metal
Step 1: Write the cation name• Cation is Ni+2
Step 2: Write the charge/ roman numeral of the cation in parenthesis
• Nickel(II)
Step 3: Write the anion name with the ending –ide• Anion is S-2 = Sulfide
Nickel(II) sulfide
Writing Formulas from names
What is the formula for potassium nitride? K = alkali metal = not a transition metal
• Cation is K+
• Anion is N-3
K3N
What is the formula of chromium (III) chloride? Roman numerals = transition metal, so charge is +3
• Cation is Cr+3
• Anion is Cl-
CrCl3
Naming Molecular Formulas Molecular compounds
2 nonmetals (right side + right side)
Uses prefixes
• Do not write mono for first nonmetal
Second nonmetal has -ide ending
Prefixes
Number of Atoms Prefix
1 Mono
2 Di
3 Tri
4 Tetra
5 Penta
6 Hexa
Examples
What is the name of PCl3? 1 P = phosphorus 3 Cl = trichloride Phosphorus trichloride
What is the formula for dihydrogen monoxide? Di = 2 H Mon = 1 O H2O