Quick Review

- Classification of Matter (end of Chapter 1 material)- Fundamental Laws- Dalton’s Atomic Theory- Cathode-Ray Tube Experiment (J.J. Thomson)- Plum Pudding Model- Alpha-Particle Bombardment Expt. (Rutherford)- Nuclear Atom- Elemental Designation- Isotopes- Periodic Table- Simple Molecule Formation- Nomenclature

Ionic Compounds

1. The cation is always written first, the anion is named second. In ionic compounds, the cation is usually a metal. When a metal is in a compound, the compound is assumed ionic.

2. The cations: (a) monoatomic metals: use base name of the metal.(b) transition metals: use base name of the metal

followed by a roman numeral indicating charge. (c) polyatomic cations: the only one to memorize

NH4+ = ammonium

3. The anions:(a) monoatomic nonmetals: use the base name of the

nonmetal, then add the -ide suffix. (b) polyatomic anions: memorize the anions in Table 2.5.

Ionic Compounds - Examples

Name the following compounds:

(a) NaCl (b) NH4 NO3(c) Li3 N

Give the molecular formula for the following compounds:

(a) Aluminum oxide(b) Chromium (III) chloride(c) Sodium sulfite

Covalent Compounds

1. The first element in the formula is named first using the base name.

2. The second element is named like an anion (base name plus -ide suffix).

3. Use prefixes to denote numbers for cations and anions (Table 2.6)

4. The prefix mono is never used for naming the first element in a formula (it is assumed).

5. Avoid awkward pronounciations Example: CO = carbon monoxide not carbon monooxide.

6. Know common names like H2 O = water, and C6 H12 O6 = glucose; memorize the names of the acids in Table 2.7 and 2.8 (as well as HClO4 , perchloric acid).

Covalent Compounds - Examples

Name the following compounds:

(a) PCl5

(b) SF6

(c) SO2

Give the molecular formula for the following compounds:

(d) Tetraphosphorous decaoxide

(e) Carbon dioxide

(f) Sulfur trioxide

TO MEMORIZE(1) Names of elements 1-36(2) Names of all alkali metals, alkaline earth metals,

halogens and noble gases.

TO MEMORIZE

TO MEMORIZE

(1) Identify a compound as being ionic or covalent. (2) Utilize the appropriate rules to name the compound.(3) Will also be asked to write out molecular formulas of compounds from a given name.

Counting by WeighingCounting individual jelly beans is a tedious process.

A more efficient process would be to count by weighing.

What do you need to know about each jelly bean in order to utilize this method?

Need to know the average mass of a jelly bean.

What does this have to do w/ Chem? We count atoms in the same way!

An atom is a million times smaller than the thickest human hair.

We must know the average mass of atoms.

Atomic Mass

12C is assigned a mass of exactly 12 atomic mass units, masses of all other atoms are relative to this standard.

Mass spectrometer is used to measure accurate atomic masses.

Relative Atomic Masses

Mass of 13C Mass of 12C

= 1.0836129

Mass of 13C = (1.0836129)(12 amu) = 13.003355 amu

The masses of all other atoms are determined in the same way.

Atomic Mass Question: Why is the atomic mass of carbon 12.01 and not 12.00?

Answer:

Question: What two things do you need to know to determine average mass?

Answer:

Example:

98.89% (12 amu) + 1.11% (13.0034 amu) = 12.01 amu

The Mole

Mole – number equal to the number of carbon atoms in exactly 12 grams of pure 12C. 6.022 x 1023 called Avogadro’s number.

One mole of Cu, Al, Fe, S, I and Hg.

A mole of anything represents 6.022 x 1023 units.

A mole of eggs represents 6.022 x 1023 eggs.

The Mole

The mole is defined such that a sample of a natural element with a mass equal to the element’s atomic mass expressed in grams contains 1 mole of atoms.

The Mole

Since the same 12C standard is used to define relative atomic masses and the mole, then the atomic mass of any element in units of grams will be the molar mass (mass of one mole of that substance) of that element.

(6.022 x 1023 atoms) 12 amu atom

= 12 g

6.022 x 1023 amu = 1 g

This relationship can be used to convert between atomic mass units and grams.

The Mole

Question: A small atomic bomb requires 4.0 moles of uranium. How many grams of uranium and how many uranium atoms does 4.0 moles represent?

Answer:

Molar Mass

Molar Mass – of a substance is the mass in grams of one mole of the compound.

To determine molar mass of a compound we must know the molecular formula.

The molecular formula tells us the actual number and kinds of atoms that make up a compound. Also tells us the mole ratios.

Calculation of Molar Mass

Example: H2 SO4

Review Example Chapter 3 #58: Chloral hydrate (C2 H3 Cl3 O2 ) is a drug

formerly used as a sedative and hypnotic. It is the compound used to make “Mickey Finns” in detective stories.

(a) Calculate the molar mass of chloral hydrate(b) What amount (moles) of chloral hydrate molecules are

in 500.0 g of chloral hydrate.(c) What is the mass in grams of 2.0 x 10-2 mol chloral

hydrate?(d) What number of chlorine atoms are in 5.0 g of chloral

hydrate?(e) What mass of chloral hydrate would contain 1.0 g of Cl?(f) What is the mass of exactly 500 molecules of chloral

hydrate?