Describing elements by their place in the periodic system
Answers are for parents and teachers.
1
Using the plan for phosphorus (Z = 15, A = 31): neutrons, outer electrons, highest oxide, hydrogen compound.
16 neutrons; 5 outer electrons; P₂O₅; PH₃.
2
Relative molecular mass of Br₂O₇ (Aᵣ(Br) = 80).
272
3
Identify the period-4 s-element with configuration ...4s².
Calcium Ca (Z = 20).
4
Arrange K, Ca and Sc in order of decreasing metallic character and explain.
K > Ca > Sc: along the period the radius shrinks and metallic character weakens.
5
Find the difference between predicted and measured relative atomic masses of germanium (72 and 72.6).
0.6