# Element X is in group 2 of the periodic table and element Y is in group 7.

Submitted by brat619 on Wed, 03/28/2012 - 20:07

1) Element X is in group 2 of the periodic table and element Y is in group 7.

a) Name the groups for the element.
b) How many balance electron for each.
c) Draw electron dot notation for each element
d) Give symbol for ion for each element.
e) Draw Lewis structure for each element.

2) In the reaction 2H2+O2=2H2O
If 16 gram hydrogen combines with 96 grams oxygen. What is the limiting reaction?

1) Element X is in group 2 of the periodic table and element Y is in group 7.

a) Name the groups for the element.  Group 2 is the alkali earth metals, Group 7 are the Halogens.
b) How many valance electron for each. X has 2, Y has 7
c) Draw electron dot notation for each element X would have 2 dots around it, Y would have 7.
d) Give symbol for ion for each element.  No enough information to determine the symbol.  Could be any one of the Group 2 or Group 7 elements.
e) Draw Lewis structure for each element.  Lewis structures and electron dot diagrams are the same.

2) In the reaction 2H2+O2=2H2O
If 16 gram hydrogen combines with 96 grams oxygen. What is the limiting reaction?

Convert both to moles:

16 g H  /  1 g/mol   =   16 moles H atoms

96 g O / 16 g/mol  =    6 moles O atoms

The balanced equation tells us that 2 moles of H are required to react with each mole of O.  16 moles of H would thus require 8 moles of O to completely react with it.  Since we only have 6 moles of O, the oxygen will run out first.  The substance that runs out first is the limiting reagent.