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Mx. Gwara @Trinity School
GO TO “Chemistry - Substance Quiz” Knowt for Unit 4
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UNIT 5: CLASSIFYING COMPOUNDS
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READING A PERIODIC TABLE
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sides of the table (H-Be; B-He)
representative elements → if ion is formed with this element, it always forms the same charge ion
middle of table (Sc - Zn)
transition metals → if ion is formed with this element, it has variability in ions
bottom of table
rare earth metals
staircase
left = metals; right = nonmetals; close by = metalloids
Al (metal, metalloid, nonmetal?)
Aluminum is a metal, an exception to the staircase.
Right to left charges, rep elements
H column: +1 (H is an exception with +1 -1)
Be column: +2
B column: +3
C column: variability
N column: -3
O column: -2
F column: -1
He column: 0
In the C column (Carbon), what are the charges for Carbon, Silicon and Germanium? (C, Si, Ge?) What about tin and lead (Sn and Pb)?
0; tin and lead have variability…
What are three exceptions to transition metals?
Zinc (Zn); Cadmium (Cd); Silver (Ag)
Charges: +2; +2; +1
Magnesium cation + Chlorine anions = MgCl2
Cl = -1 … so Mg = +2
Predict the formula between magnesium cations and sulfur anions.
Sulfur is -2 (periodic table)
Magnesium is +2 (last question)
Formula: MgS
The particle diagrams for the compounds in the last few questions should look like molecules. Should they be represented with molecules?
NO. They have charge, thus, they are ions, not molecules!
Predict the formulas for the following compounds:
potassium and oxygen
calcium and selenium
K = +1 ; O = -2; Formula: K2O
Ca = +2; Se = -2; Formula: CaSe
Would you expect each of the following atoms to gain or lose electrons when forming ions? What ion is the most likely in each case?
Ra
In
P
Te
Br
Rb
Ra → +2 → lose
In → +3 → lose
P → -3 → gain
Te → -2 → gain
Br → -1 → gain
Rb → +1 → lose
