The AP Chemistry’s Basic Unit Review/Summary
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<img src="/icons/arrow-left-basic_gray.svg" alt="/icons/arrow-left-basic_gray.svg" width="40px" /> Back AP Chemistry
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Basic Course Unit Review
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<img src="/icons/list_gray.svg" alt="/icons/list_gray.svg" width="40px" /> Table of Contents
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Unit 1: Atomic Structure and Properties
1.1 Moles and Molar Mass
- Avogadro’s Number - 6.022 × 10²³
- Named in honor of Avogadro, who is not the one who discovered it.
- Molar Mass
- A substance’s molecular weight is defined by the ratio between mass and the amount of substance measured in moles.
- “Mass per Mole”
- 1 mole is also Avogadro’s Number (6.022 × 10²³), the weight of an element on the periodic table, and 22.4L (only for gases at standard temperature and pressure or STP).
1.2 Mass Spectroscopy of Elements
- Atomic Mass Unit (amu)
- Equal to the mass of 1 proton or 1 neutron
- Atomic masses on the periodic table are the average mass of all the isotopes and their percent abundance.
- 1/12 the mass of a carbon-12 atom, an atom that has 6 protons and 6 neutrons.
- Isotopes
- Element with the same number of protons and electrons (same element) but differing numbers of neutrons.
- Isotopes have the same atomic number but different atomic masses.
- Mass Spectroscopy
- The most accurate method for identifying the amount and element present in a sample.
- Mass Spectrum
- Graph that shows the percent abundance of the ions of certain isotopes and their mass/charge.
- X-Axis: Labeled as Atomic Mass (u) or Mass-To-Charge Ratio. It just means the mass number.
- Y-Axis: Percent Abundance. It just means the percent of the isotope in nature.
- To figure out what element is shown in the graph, multiply each mass number by its percentage.
1.3 Elemental Composition of Pure Substances
- Empirical Formula
- Simplest whole number ratio of each element in a compound.
- Does not always show the actual number of elements in a compound.
- Example: $CH_2O$
- Molecular Formula
- Shows the exact number (mols) and types of elements present in a compound
- Example: $C_6H_{12}O_6$
1.4 Composition of Mixtures
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Matter |
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Mixture |
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Pure Substance |
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| Homogeneous |
Heterogeneous |
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Compound |
Element |
- Matter: Anything that has mass and occupies “space”
- Mixtures: Physically made up of 2 or more substances
- Homogeneous Mixtures (A Solution)
- Composed of 2(+) substances and is Uniform in Composition
(made with the same thing throughout)
- Usually inseparable
- Heterogeneous Mixtures
- Composed of 2(+) elements or compounds and is Ununiform in Composition
(not made with the same thing throughout, like air)
- Usually separable
- Pure Substance: Has consistent composition and properties
- Element: A substance that cannot be broken into simpler substances
- Compound: Two or more elements chemically combined that can be broken into simpler substances
- Separating Mixtures
- Physical changes that can be made to separate mixtures into pure substances:
- Distillation
- The process of separating the components of a liquid mixture through vaporization of the liquid, then condensing it back to its pure liquid state.
- Filtration
- Used for mixtures that contain undissolved (insoluble) solids in the liquid by filtering the mixture through a filtering agent (i.e., mesh), leaving the solids on the filtering agent.
- Chromatography
- Method of separation where components are distributed between two phases: mobile and stationary.
1.5 Atomic Structure and Electron Configuration
