GOB Chemistry Study Guide: Matter, Energy, Elements, and Atomic Structure

Test 1 Study Guide: GOB Chemistry

Overview

This study guide covers foundational topics in General, Organic, and Biological (GOB) Chemistry, including matter and energy, the periodic table, atomic structure, and electron energy. The guide is structured according to the test outline and content areas specified in the provided syllabus.

Matter and Energy

Classification of Matter

• Pure Substances: Materials with a fixed composition and distinct properties. Examples: elements (e.g., O2, Fe) and compounds (e.g., H2O, NaCl).

• Mixtures: Physical combinations of two or more substances. Can be homogeneous (uniform composition, e.g., saltwater) or heterogeneous (non-uniform, e.g., salad).

States of Matter

• Solids: Definite shape and volume; particles are closely packed.

• Liquids: Definite volume, no definite shape; particles are less tightly packed than solids.

• Gases: No definite shape or volume; particles are far apart and move freely.

Physical vs. Chemical Changes

• Physical Change: Alters the form or appearance but not the composition (e.g., melting ice).

• Chemical Change: Produces new substances with different properties (e.g., rusting iron).

Changes of State

• Melting: Solid to liquid

• Freezing: Liquid to solid

• Boiling/Evaporation: Liquid to gas

• Condensation: Gas to liquid

• Sublimation: Solid to gas

• Deposition: Gas to solid

Energy and Heat

• Specific Heat: The amount of heat required to raise the temperature of 1 gram of a substance by 1°C.

$q = m \times c \times \Delta T$

• q: heat (Joules or calories)

• m: mass (grams)

• c: specific heat (J/g°C)

• ΔT: change in temperature (°C)

Heating and Cooling Curves

• Boiling Point: Temperature at which a liquid becomes a gas.

• Heating/Cooling Curve: Graph showing temperature change as heat is added or removed.

The Periodic Table and Elements

Element Names and Symbols

• Be able to spell and recognize the chemical symbols for common elements (see table below).

Element	Symbol
Aluminum	Al
Argon	Ar
Arsenic	As
Barium	Ba
Boron	B
Bromine	Br
Cadmium	Cd
Calcium	Ca
Carbon	C
Chlorine	Cl
Chromium	Cr
Cobalt	Co
Copper	Cu
Fluorine	F
Gold	Au
Helium	He
Hydrogen	H
Iodine	I
Iron	Fe
Lead	Pb
Lithium	Li
Magnesium	Mg
Manganese	Mn
Mercury	Hg
Neon	Ne
Nickel	Ni
Nitrogen	N
Oxygen	O
Phosphorus	P
Potassium	K
Sulfur	S
Silicon	Si
Selenium	Se
Tin	Sn
Uranium	U
Zinc	Zn

Periodic Table Organization

• Periods: Horizontal rows (indicate energy levels).

• Groups: Vertical columns (elements with similar properties).

• Metals: Left and center; good conductors, malleable, shiny.

• Nonmetals: Right side; poor conductors, brittle, dull.

• Metalloids: Border between metals and nonmetals; properties of both.

Properties of Metals, Nonmetals, and Metalloids

Type	Properties
Metals	Shiny, malleable, ductile, good conductors
Nonmetals	Dull, brittle, poor conductors
Metalloids	Intermediate properties, semiconductors

Atomic Structure and Theory

Atomic Theory

• Atoms are the basic units of matter, composed of protons, neutrons, and electrons.

• Protons: Positively charged, found in the nucleus.

• Neutrons: Neutral, found in the nucleus.

• Electrons: Negatively charged, found in orbitals around the nucleus.

Atomic Number, Mass Number, and Isotopes

• Atomic Number (Z): Number of protons in the nucleus; defines the element.

• Mass Number (A): Total number of protons and neutrons.

• Isotopes: Atoms of the same element with different numbers of neutrons.

$\text{Mass Number} = \text{Number of Protons} + \text{Number of Neutrons}$

Calculating Atomic Mass from Isotopes

• Atomic mass is the weighted average of all naturally occurring isotopes.

$\text{Atomic Mass} = \sum (\text{isotope mass} \times \text{fractional abundance})$

Electron Configuration

• Electrons are arranged in shells, subshells, and orbitals.

• Shells: Principal energy levels (n = 1, 2, 3, ...).

• Subshells: s, p, d, f (types of orbitals within shells).

• Electron configuration shows the distribution of electrons among orbitals.

Example: $1s^2 2s^2 2p^6 3s^2 3p^6 4s^1$ (for potassium, K)

Periodic Trends

• Atomic Size: Increases down a group, decreases across a period.

• Ionization Energy: Energy required to remove an electron; increases across a period, decreases down a group.

• Metallic Character: Increases down a group, decreases across a period.

Lab: Elements

• Be familiar with the names and symbols of common elements.

• Understand how to identify elements based on their properties and periodic table position.

Example Application

• Classifying Matter: Saltwater is a homogeneous mixture; iron is a pure substance (element).

• Physical Change: Melting ice; Chemical Change: Burning wood.

• Calculating Atomic Mass: If chlorine has two isotopes, Cl-35 (75%) and Cl-37 (25%): $(35 \times 0.75) + (37 \times 0.25) = 35.5$

Additional info: Students will not have access to a periodic table during the test, so memorization of key element names and symbols is essential.