Chem chapter 5

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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 (-)


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