General Chemistry Exam 1 Study Guide: SI Units, Metric Prefixes, Naming, Ions, and Elements

SI Units in Chemistry

Fundamental SI Units

The International System of Units (SI) provides standard units for scientific measurements. These units are essential for consistency in chemical calculations and laboratory work.

• Length: Meter (m)

• Mass: Kilogram (kg)

• Time: Second (s)

• Temperature: Kelvin (K)

• Amount of substance: Mole (mol)

Temperature conversions are also important in chemistry, especially between Celsius and Kelvin.

Metric Prefixes

Common Metric Prefixes and Their Meanings

Metric prefixes are used to express multiples or fractions of SI units. Understanding these prefixes is crucial for converting between units.

Prefix	Abbreviation	Meaning	Example
Giga	G	$10^9$ (Billion)	1 gigameter = $1 \times 10^9$ m
Mega	M	$10^6$ (Million)	1 megagram = $1 \times 10^6$ g
Kilo	k	$10^3$ (Thousand)	1 kilometer = $1 \times 10^3$ m
Deci	d	$10^{-1}$ (Tenth)	1 decimeter = $1 \times 10^{-1}$ m
Centi	c	$10^{-2}$ (Hundredth)	1 centimeter = $1 \times 10^{-2}$ m
Milli	m	$10^{-3}$ (Thousandth)	1 milligram = $1 \times 10^{-3}$ g
Micro	μ	$10^{-6}$ (Millionth)	1 microliter = $1 \times 10^{-6}$ L
Nano	n	$10^{-9}$ (Billionth)	1 nanometer = $1 \times 10^{-9}$ m
Pico	p	$10^{-12}$ (Trillionth)	1 picogram = $1 \times 10^{-12}$ g
Femto	f	$10^{-15}$ (Quadrillionth)	1 femtosecond = $1 \times 10^{-15}$ s

Key Conversions:

• $1 \text{ cm}^3 = 1 \text{ mL}$

• $1 \text{ mol} = 6.022 \times 10^{23}$ particles (Avogadro's number)

Naming Molecular Compounds: Prefixes

Numerical Prefixes for Molecular Compounds

Prefixes are used to indicate the number of atoms of each element in a molecular compound.

Number	Prefix
1	mono
2	di
3	tri
4	tetra
5	penta
6	hexa
7	hepta
8	octa
9	nona
10	deca

Example: $\text{CO}_2$ is named "carbon dioxide" (di- for two oxygens).

Transition Metal Charges

Common Charges of Transition Metals

Transition metals can form ions with different charges. It is important to memorize the common charges for naming and writing formulas.

• Cr2+, Cr3+: Chromium (II) or Chromium (III) ion

• Mn2+: Manganese (II) ion

• Fe2+, Fe3+: Iron (II) or Iron (III) ion

• Cu+, Cu2+: Copper (I) or Copper (II) ion

• Ag+: Silver ion

• Hg22+, Hg2+: Mercury (I) or Mercury (II) ion

• Zn2+: Zinc ion

• Pb2+: Lead ion

• Co2+, Co3+: Cobalt (II) or Cobalt (III) ion

Example: $\text{Fe}^{3+}$ is called iron (III) ion.

Polyatomic Ions

Common Polyatomic Ions and Their Formulas

Polyatomic ions are ions composed of two or more atoms covalently bonded, carrying a net charge. Memorizing their names and formulas is essential for writing chemical equations and naming compounds.

Name	Formula
Acetate	CH3COO-
Carbonate	CO32-
Hydrogen carbonate (bicarbonate)	HCO3-
Nitrate	NO3-
Nitrite	NO2-
Phosphate	PO43-
Sulfate	SO42-
Sulfite	SO32-
Hydroxide	OH-
Ammonium	NH4+

Example: $\text{NaNO}_3$ contains the nitrate ion ($\text{NO}_3^-$).

Elements to Memorize from the Periodic Table

Key Groups and Periods

Certain elements are commonly referenced in introductory chemistry. Memorizing their symbols and names is helpful for chemical equations and nomenclature.

• Period 1

• Period 2

• Period 3

• Group 1 Metals

• Noble Gases

• Selected Transition Metals: Cr, Cu, Ni, Zn, Co, Au, Ag, Fe, Pb

Example: Na is the symbol for sodium, a Group 1 metal.