GOB Chemistry Study Guide: Matter, Measurement, and the Periodic Table

Ch. 1 Matter and Measurement

Introduction to Matter and Measurement

This chapter introduces the foundational concepts of chemistry, including the classification of matter, measurement techniques, and the use of the metric system. Understanding these basics is essential for further study in chemistry.

• Matter: Anything that has mass and occupies space.

• Measurement: The process of obtaining the magnitude of a quantity relative to an agreed standard.

Symbols and Formulas

• Periodic Table Symbols: Each element is represented by a unique one- or two-letter symbol (e.g., H for hydrogen, O for oxygen).

• Chemical Formulas: Indicate the types and numbers of atoms in a compound. For example, H2O has two hydrogen atoms and one oxygen atom.

Chemical Reactions

• Reactants vs. Products: Reactants are substances present before a chemical reaction; products are formed as a result of the reaction.

• Chemical Equation Example: $2H_2 + O_2 \rightarrow 2H_2O$

Classification of Matter

• Mixture: Physical combination of two or more substances.

• Substance: Matter with a fixed composition (element or compound).

• Homogeneous Mixture: Uniform composition throughout (e.g., saltwater).

• Heterogeneous Mixture: Non-uniform composition (e.g., salad).

• Element: Pure substance of one type of atom.

• Compound: Substance composed of two or more elements chemically combined.

Physical and Chemical Changes

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

• Chemical Change: Alters composition, forming new substances (e.g., rusting iron).

• Indicators of Chemical Change: Color change, gas production, precipitate formation, energy change.

Properties of Matter

• Physical Properties: Observed without changing composition (e.g., melting point, density).

• Chemical Properties: Observed during a chemical change (e.g., flammability).

States of Matter

• Solid: Definite shape and volume.

• Liquid: Definite volume, indefinite shape.

• Gas: Indefinite shape and volume.

Measurement and Units

• Accuracy: Closeness to the true value.

• Precision: Reproducibility of measurements.

• SI Units: Standard units for scientific measurement (e.g., meter for length, kilogram for mass, second for time).

• Metric Prefixes:

  • kilo (k): $10^3$

  • centi (c): $10^{-2}$

  • milli (m): $10^{-3}$

  • micro (μ): $10^{-6}$

  • nano (n): $10^{-9}$

Significant Figures

• Significant Figures: Digits in a measurement that are known with certainty plus one estimated digit.

• Rules: Nonzero digits are always significant; zeros between nonzero digits are significant; leading zeros are not significant; trailing zeros are significant if after a decimal point.

• Rounding: Round to the correct number of significant figures based on the operation performed.

Dimensional Analysis (Unit Conversions)

• Dimensional Analysis: A method to convert one unit to another using conversion factors.

• Example: To convert 5.0 cm to meters: $5.0\ \text{cm} \times \frac{1\ \text{m}}{100\ \text{cm}} = 0.050\ \text{m}$

Graphing and Data Interpretation

• Graphing: Plot data points, determine the slope, and interpret relationships between variables.

• Reporting: Answers should be reported to the correct number of significant figures.

Temperature Scales

• Kelvin (K): Absolute temperature scale.

• Celsius (°C): Water freezes at 0°C, boils at 100°C.

• Fahrenheit (°F): Water freezes at 32°F, boils at 212°F.

• Conversions:

  • $K = ^\circ C + 273.15$

  • $^\circ F = (9/5)\times ^\circ C + 32$

  • $^\circ C = (5/9)\times (^\circ F - 32)$

Specific Heat and Calorimetry

• Specific Heat (c): Amount of heat required to raise the temperature of 1 g of a substance by 1°C.

• Formula: $q = m \cdot c \cdot \Delta T$ Where $q$ = heat (J), $m$ = mass (g), $c$ = specific heat (J/g°C), $\Delta T$ = change in temperature (°C).

• Water's Specific Heat: $4.184\ \text{J/g}^\circ\text{C}$

• Calorimetry: Measurement of heat flow in a chemical or physical process.

Ch. 2 Atoms and the Periodic Table

Atomic Structure

• Proton: Positively charged particle in the nucleus; mass ≈ 1 amu.

• Neutron: Neutral particle in the nucleus; mass ≈ 1 amu.

• Electron: Negatively charged particle outside the nucleus; mass ≈ 0.0005 amu.

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

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

Isotopes and Atomic Mass

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

• Average Atomic Mass: Weighted average of all naturally occurring isotopes. Formula: $\text{Atomic mass of element} = \frac{\text{mass of isotope 1} \times \%\text{isotope 1}}{100} + \frac{\text{mass of isotope 2} \times \%\text{isotope 2}}{100}$

Electron Configuration and Quantum Model

• Quantum Mechanical Model: Describes electrons in terms of probability distributions.

• Sublevels: s, p, d, f, g; each has a characteristic shape and number of orbitals.

• Orbitals: Regions in space with a high probability of finding an electron; each orbital holds a maximum of 2 electrons.

• Order of Filling Orbitals: Orbitals fill in order of increasing energy (Aufbau principle): 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p.

• Electron Configuration Example: Sodium (Na): $1s^2 2s^2 2p^6 3s^1$

• Noble Gas Shorthand: Use the previous noble gas in brackets, then continue configuration. Example: Sodium: [Ne]$3s^1$

Valence and Core Electrons

• Valence Electrons: Electrons in the outermost shell; involved in chemical bonding.

• Core Electrons: Electrons in inner shells; not usually involved in bonding.

Summary Table: Subatomic Particles

Particle	Symbol	Charge	Location	Relative Mass
Proton	p+	+1	Nucleus	1
Neutron	n0	0	Nucleus	1
Electron	e-	-1	Outside nucleus	~0

Summary Table: Metric Prefixes

Prefix	Symbol	Factor
kilo	k	103
centi	c	10-2
milli	m	10-3
micro	μ	10-6
nano	n	10-9

Additional info:

• Students should be able to perform calculations involving significant figures, unit conversions, and calorimetry problems.

• Understanding how to interpret and construct electron configurations is essential for predicting chemical behavior.