Study Guide for Exam II
(What will be supplied? Charge chart, solubility chart, & regular periodic table)
Which elements form diatomic molecules? Remember if you see the word ‘gas,’ find it on the
periodic table. Is it Br or Br2? This make a big difference if you’re calculating molar or formula
mass. (Remember molar mass and formula mass would be the same number. They are
acquired by adding up the atomic weights from the periodic table; the difference is that molar
mass has the units of grams while formula mass has the units amu.)
How do you distinguish between covalent molecules (only nonmetals involved in bonding) and
ionic formula units (metal + nonmetals…OR the presence of+.NH
Acids
4 also break up to form
H+ and an anion.)
Be able to manipulate subscripts so that you obtain a neutral compound. This may mean doin
a criss-cross (swap and drop) of charges. Equal and opposite charges won’t be swapped and
dropped because it is already neutral.
If you were given a compound already put together, can you successfully undo the criss-cross
to figure out the charges on the cation and anion? Alternatively you can do simple math
equations. For example, SnO2… It is neutral, so if you have two 2-’s from oxygen giving a total
charge of 4-. What will that make Sn? 4+
Note: When you write a compound, the more metallic atom will be listed first (the atom
farther to the left on the table.) The cation is listed before the anion. If you have only
nonmetals, choose the nonmetal farther to the left and/or farther down the group.
Know that when you have covalent compounds, you use prefixes when naming them. If you
have a compound that is dinitrogen tetroxide, N2O4, do NOT reduce. You will reduce ionic
compounds (metal + nonmetal) because ionic compounds are written as formula units, the
lowest ratio of cation to anion. (Have your prefixes memorized, as well as the polyatomic ions
you had to previously memorize.)
When do you use roman numerals when naming a compound?
What’s the difference in naming rules between binary acids such as HCl and oxyacids
containing a polyatomic ion with oxygen?
Oxyacids: polyatomic ion ends with -ate? Root -ic acid.
Polyatomic ion ends with -ite? Root -ous acid
(What will be supplied? Charge chart, solubility chart, & regular periodic table)
Which elements form diatomic molecules? Remember if you see the word ‘gas,’ find it on the
periodic table. Is it Br or Br2? This make a big difference if you’re calculating molar or formula
mass. (Remember molar mass and formula mass would be the same number. They are
acquired by adding up the atomic weights from the periodic table; the difference is that molar
mass has the units of grams while formula mass has the units amu.)
How do you distinguish between covalent molecules (only nonmetals involved in bonding) and
ionic formula units (metal + nonmetals…OR the presence of+.NH
Acids
4 also break up to form
H+ and an anion.)
Be able to manipulate subscripts so that you obtain a neutral compound. This may mean doin
a criss-cross (swap and drop) of charges. Equal and opposite charges won’t be swapped and
dropped because it is already neutral.
If you were given a compound already put together, can you successfully undo the criss-cross
to figure out the charges on the cation and anion? Alternatively you can do simple math
equations. For example, SnO2… It is neutral, so if you have two 2-’s from oxygen giving a total
charge of 4-. What will that make Sn? 4+
Note: When you write a compound, the more metallic atom will be listed first (the atom
farther to the left on the table.) The cation is listed before the anion. If you have only
nonmetals, choose the nonmetal farther to the left and/or farther down the group.
Know that when you have covalent compounds, you use prefixes when naming them. If you
have a compound that is dinitrogen tetroxide, N2O4, do NOT reduce. You will reduce ionic
compounds (metal + nonmetal) because ionic compounds are written as formula units, the
lowest ratio of cation to anion. (Have your prefixes memorized, as well as the polyatomic ions
you had to previously memorize.)
When do you use roman numerals when naming a compound?
What’s the difference in naming rules between binary acids such as HCl and oxyacids
containing a polyatomic ion with oxygen?
Oxyacids: polyatomic ion ends with -ate? Root -ic acid.
Polyatomic ion ends with -ite? Root -ous acid
