Summary Chapter 1-2

General, Organic, & Biological ChemistryJanice Gorzynski Smith

CH 1-2 Concepts to be Familiar With

Classification of matter: pure substances & mixtures Homogeneous vs Heterogeneous

Distinguish the difference between chemical and physical properties & changes

We represent uncertainty with significant figures You do not need to memorize Sig Fig rules

Scientific Notation Conversions within the metric system and non metric units

Temperature conversions Density & Specific gravity Familiarity with how compounds will be drawn

Molecular formulas Structure of an atom: protons, neutrons, electrons

Atomic number, isotope mass number, atomic weight Navigate the periodic table: properties shared within a group, trends,

metals/metalloids/nonmetals Determine valance electrons & draw electron dot representations Ionization Energy & Atomic Size

Conversions & Equations To Memorize

Unit Conversions

For metric units (m, kg, s, K, mole):mega (M) 106

kilo (k) 103

centi (c) 10-2

milli (m) 10-3

micro (μ) 10-6

nano (n) 10-9

Pico (p) 10-12

Time conversions: dhrms

1 mL = 1 cm3

T(kelvin) = T(°C) + 273.15

Equations

Density = mass / Volumed = m/V

dH2O = 1 g/mL = 1 g/cm3

Specific Gravity = density substance / density of water

Coefficient:A number between1 and 10.

y x 10x

Exponent:Any positive or negativewhole number.

Elements & Molecules

X = Element symbol (ie O = oxygen)A = Isotope Mass Number = # protons + # neutronsZ = Atomic Number = # protons

6

C12.01

atomic number

element symbol

atomic weight (amu) = weighted average of atomic weight of isotopes

Elements on the Periodic

Table

Molecular Formula: AxBy Ex: CH3O

H C H

H

H

Drawing Molecules:

Methane CH4

Properties of Groups

1A 2A B B 7A 8A

Alkali Metals Alkaline Earth Metals

Transition Metals

Lanthanide & Actinide

Halogens Nobel Gases

Very reactive

Metals except for H

+1 ions

React with Oxygen to form compounds that dissolve into alkaline solutions in water

Reactive

+2 ions

Oxygen compounds are strongly alkaline

Many are not water soluble

Metals

Form ions with several different charges (oxidation states)

Tend to form +2 and +3 ions

Lanthanides 58 – 71

Actinides 90 – 103

Actinides are radioactive

Reactive

Form diatomic molecules in elemental state

-1 ions

Salts with alkali metals

Inert

Heavier elements have limited reactivity

Do not form ions

Monoatomic gases

Properties of Metals, Nonmetals, Metalloids

Metals Nonmetals Metalloids

• Metallic luster, malleable, ductile, hardness variable

• Conduct heat and electricity

• Solids at room temperature with the exception of Hg

• Chemical reactivity varies greatly: Au, Pt unreactive while Na, K very reactive

• Brittle, dull

• Insulators, non-conductors of electricity and heat

• Chemical reactivity varies

• Exist mostly as compounds rather then pure elements

• Many are gases, some are solids at room temp, only Br2 is a liquid.

• Properties intermediate between metals and nonmetals

• Metallic shine but brittle

• Semiconductors: conduct electricity but not as well as metals: examples are silicon and germanium

Valence Electrons

1 2 X X X X X X X X X X 3 4 5 6

Count the number of elements in the row (period) that lead up to the element (Se). Remember, do NOT count the transition metals, lacthanides, and actinides.

Example: Determine the valence electrons of Selenium (Se):1. Find Se on the periodic table2. Focus on just the row (period) Se is in3. Count the number of electrons in the s

and p orbitals (ie, count to Se from the left side of the row)

SeElectron Dot Symbols:

Represent the valence electrons by drawing them around the element symbol for Selenium.

Periodic Trends

Ionization EnergyINCREASING

SizeINCREASING