EasyChemistryHigh School (11–12)The Periodic Table › Periodic TrendsThe Periodic Table › Groups and FamiliesConceptualBoard Exam
Use the valences of the groups to write three formulas…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Use the valences of the groups to write three formulas. The pairs are calcium (group 2) with phosphorus (group 15), silicon (group 14) with chlorine (group 17), and aluminium (group 13) with oxygen (group 16).
Need a reminder? The key ideaShow
Electronegativity is the pull of an atom in a compound on a shared pair of electrons; fluorine is 4.0 on the Pauling scale. It rises across a period and falls down a group. Valence is the number of outer electrons, or eight minus it. Oxides are basic on the left of a period, amphoteric in the middle and acidic on the right.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. Valences. Calcium , phosphorus , silicon , chlorine , aluminium , oxygen .
Step 2. Calcium and phosphorus. Cross over: .
Step 3. Silicon and chlorine. .
Step 4. Aluminium and oxygen. .
Answer: , and .
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