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Questions and Answers
How many significant figures are in the number 0.004050?
How many significant figures are in the number 0.004050?
Which of the following numbers contains exactly three significant figures?
Which of the following numbers contains exactly three significant figures?
Which number has the least amount of significant figures?
Which number has the least amount of significant figures?
How many significant figures are present in the result of the calculation: $204.1 imes 0.050$?
How many significant figures are present in the result of the calculation: $204.1 imes 0.050$?
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Which of the following measurements has five significant figures?
Which of the following measurements has five significant figures?
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Which of the following is an example of a physical property?
Which of the following is an example of a physical property?
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Which property would indicate a change in the substance when measured?
Which property would indicate a change in the substance when measured?
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What distinguishes physical properties from chemical properties?
What distinguishes physical properties from chemical properties?
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Which of the following is NOT considered a physical property?
Which of the following is NOT considered a physical property?
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Which of these properties can change upon a change in temperature?
Which of these properties can change upon a change in temperature?
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Study Notes
Significant Figures (Sig Figs)
- Non-zero digits are always significant.
- Zeros between significant digits are significant.
- Leading zeros are not significant.
- Trailing zeros are significant if there is a decimal point.
- Addition/Subtraction: Round the answer to the least number of decimal places.
- Multiplication/Division: Round the answer to the least number of significant figures.
Unit Conversions
- 1 mL = 0.001 L (Divide by 1000)
- 1 L = 1000 mL (Multiply by 1000)
- 1 g = 1000 mg (Multiply by 1000)
- 1 mg = 0.001 g (Divide by 1000)
- 1 km = 1000 m
- 1 m = 100 cm
- 1 cm = 10 mm
Atoms, Elements, and Compounds
- Atom: The smallest unit of an element that retains its properties.
- Element: A pure substance made of only one type of atom.
- Compound: A substance made of two or more different elements chemically bonded.
States of Matter
- Solid: Definite shape and volume. Particles are closely packed.
- Liquid: Definite volume, takes the shape of its container. Particles can move around.
- Gas: No definite shape or volume. Particles are far apart and move freely.
Physical vs. Chemical Change
- Physical Change: Does not alter the chemical composition (e.g., melting, freezing, cutting).
- Chemical Change: Results in the formation of new chemical substances (e.g., combustion, rusting).
Physical vs. Chemical Properties
- Physical Property: Observed or measured without changing the substance (e.g., color, melting point, density).
- Chemical Property: Describes a substance's ability to undergo a chemical change (e.g., flammability, reactivity with acids).
Dalton's Atomic Theory
- All matter is made of atoms.
- Atoms of the same element are identical.
- Atoms combine in simple whole-number ratios to form compounds.
- Chemical reactions involve the rearrangement of atoms.
Atomic Models
- J.J. Thomson: Discovered the electron; atom has a positive charge and negatively charged particles.
- Ernest Rutherford: Discovered the nucleus; atom mostly empty space.
- Niels Bohr: Electrons orbit the nucleus in fixed energy levels.
Structure of the Atom
- Protons: Positive charge, in the nucleus.
- Neutrons: Neutral charge, in the nucleus.
- Electrons: Negative charge, outside the nucleus.
Periodic Table
- Periodic: Repeating trends/patterns in elements.
- Elements are arranged by increasing atomic number.
- Groups/Families (vertical): Similar chemical properties.
- Periods (horizontal): Gradual changes in properties.
Families on the Periodic Table
- Alkali Metals: Highly reactive with water, Group 1.
- Alkali Earth Metals: Reactive, Group 2.
- Transition Metals: Groups 3-12; can form multiple charges.
- Halogens: Reactive, Group 17. form salts with metals.
- Noble Gases: Inert, non-reactive, Group 18.
Isotopes
- Isotopes are atoms of the same element with different numbers of neutrons.
Mass Spectrum
- Shows the relative abundance of isotopes of an element.
- Used to identify the element.
Naming Ionic Compounds
- Binary Ionic Compounds: Composed of two elements. Name the cation (metal) first, then the anion (non-metal).
- Ternary Ionic Compounds: Contain a polyatomic ion. Name the cation first, then the polyatomic ion.
- Ionic Compounds with Multiple Charges: Indicate the charge in Roman numerals (e.g., Iron(III) chloride).
Empirical Formula
- Simplest ratio of elements in a compound
- Find the percent each element takes up and divide by the molar mass of each element, then divide each mole number by the smallest number and that gives you a ratio.
Percent Composition
- Percent of an element in a compound = (mass of element in compound / molar mass of compound) × 100.
Laws of Conservation in Chemical Reactions
- Law of Conservation of Mass: Mass is neither created nor destroyed in a chemical reaction; balance atoms on both sides of the equation.
Kinetic Molecular Theory of Gases
- Gases are composed of constantly moving particles.
- Particles are far apart, negligible volume.
- Collisions are elastic (no energy lost).
Gas Laws
- Boyle's Law: P₁V₁ = P₂V₂ (Pressure and volume are inversely related at constant temperature).
- Charles' Law: V₁/T₁ = V₂/T₂ (Volume and temperature are directly related at constant pressure).
- Gay-Lussac's Law: P₁/T₁ = P₂/T₂ (Pressure and temperature are directly related at constant volume).
- Ideal Gas Law: PV = nRT (Relates pressure, volume, temperature, and moles).
Stoichiometry
- Use balanced chemical equations to convert between moles of reactants and products.
- Limiting Reactant: The reactant that runs out first and determines product amount.
- Excess Reactant: Left over after the reaction is complete.
Percent Yield
- Percent Yield = (Actual Yield / Theoretical Yield) × 100.
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Description
Test your knowledge on significant figures, unit conversions, and the basic concepts of atoms, elements, and compounds. Additionally, explore the different states of matter and their properties. This quiz is perfect for students mastering fundamental science concepts.
