Chem chapter 5
What is the formula for an ionic compound made of magnesium (Mg) and sulfur (S)?
MgS
How many of each type of atoms are there in the formula NH4C2H3O2?
N = 1, H = 7, C = 2, O = 2
Carbon is considered which of the following?
atomic element
elements are
atomic or molecular
the charge of a metal ion is
the same as the group number, ex: Li is in group 1. Li+. Ca is in group 2. Ca2+
When elements combine to form compounds:
their properties change completely.
molecular elements
these elements exist as diatomic molecules, two aoms of that element bonded together as their basic units.
atomic elements
those that exist in nature with single atoms as their basic units (most elements)
structural formula
uses lines to represent chemical bonds and shows how the atoms in a molecule are connected to each other
pure substances are
elements or compounds
molecular formula
gives the actual number of atoms of each element in a molecule of the compound. Ex: Hydrogen peroxide H2O2
empirical formula
gives the relative umber of atoms of each element in a compound. It gives the lowest whole-number ratio in molecular. Ex: Hydrogen peroxide: HO
What is the proper name for HBr (aq)?
hydrobromic acid
What is the system name for Fe3+ symbol ion? Hint: see table 5.4 p.145
iron(III) ion
When cations are formed, atoms:
lose valence electrons
compounds are
molecular or ionic
naming compounds.
name of cation (metal) ---> charge of cation in roman numerals in parentheses --> base of anion (nonmetal) +ide. Ex: FeCl3 = iron(III) chloride
Which among the following elements does NOT exist as a diatomic molecule in nature?
neon
Cyanocobalamin, C63H88CoN14O14P, is vitamin B12. What is the number of atoms in one molecule of vitamin B12?
181
The charge of a vanadium ion in the compound V2O5 is:
5+
Mass ratio formula:
(mass of largest element x number of atoms) / (mass of smaller element x number of atoms)
If the mass ratio of K to F in a compound is 2.06 : 1, how many grams of F are needed to react with 2.30 g of K?
1.12
What is the oxygen-to-sulfur mass ratio of sulfur dioxide (SO2)? Hint: Atomic mass for oxygen, (O) - 16.00amu; atomic mass for sulfur (S) - 32.06amu
1
What is the formula mass for potassium nitrate? Hint: Atomic mass Potassium (K) - 39.10 amu; Atomic mass Oxyden (O) - 16 amu; Atomic Mass Nitrogen (N) - 14.01 amu. The formula for Nitrate ion - NO3-
101.10amu
What is the formula mass of copper(II) fluoride (CuF2)? Hint: the atomic mass of Cu 63.55 amu; the atomic mass of F 19.00 amu
101.55
How many total atoms are in the formula Al2(CO3)3?
14
What is the oxygen-to-hydrogen mass ratio for H2O2?
16
Suppose an unknown compound XY has an X-to-Y mass ratio of 4.0 (X/Y = 4). If decomposition of compound XY gives 12.0 grams of X, then how many grams of Y must form?
3.0 grams
What is the formula for an ionic compound made of aluminum (Al) and oxygen (O)?
Al2O3
The law of constant composition states:
All samples of a given compound have the same proportions of their constituent elements.
Which metal atom below cannot form a cation of several different charges?
Ba
What is the formula for an ionic compound made of barium (Ba) and nitrogen (N)?
Ba3N2
why is the formula for table salt NaCl, and no ClNa?
Chemical formulas list the most metallic elements first. The further right the element is on the periodic table, the metallic character decreases. The further down the element is on the periodic table, the metallic character increases. Sodium is far more metallic than Chlorine, therefore it is listed first in the formula.
charge of a nonmetal is group number -8.
Ex: N is in group 15 or 5A. 5-8 = -3. N3-
A certain oxyacid is derived from the oxyanion SO42-. The formula for the oxyacid is:
H2SO4
acids begin with the element:
Hydrogen
Mass ratio example:
If we decompose an 18.0-g sample of water (H2O), we would get 16.0 g of oxygen and 2.0 g of hydrogen, or an oxygen-to-hydrogen mass ratio of: 16.0g of Oxygen / 2.0g of Hydrogen = 8.0 or 8.0:1
IUPAC
International Union of Pure Applied Chemistry. They set the rules for naming compounds.
how to write a formula for ionic compounds
Ionic compound: Al3+ O2- = Al2O3. The ionic charge of the elements each others subscript.
The oxygen-to-hydrogen mass ratio of water is always 8.0 is an example of what fundamental law?
Law of constant composition
What is the correct formula for a compound that has three oxygen atoms and one sulfur atom?
SO3
Which of the following statements about chemical formulas is FALSE?
The subscripts represent the relative mass of each type of atom in the compound.
polyatomic ion
a group of atoms with a charge
molecular compounds
compounds formed from two or more nonmetals
Ionic compounds
contain one or more cations (metals) paired with one or more anions (nonmetals). Cations are metals (+), anions are nonmetals (-)
