Chemistry: Elements, Compounds, and Mixtures

Study Notes

Defining Elements, Compounds, and Mixtures

Element: A pure substance that cannot be broken down into simpler substances by chemical means. Examples include hydrogen (H), oxygen (O), and gold (Au).
Compound: A substance formed by the chemical combination of two or more different elements in a fixed ratio. Examples include water (H₂O), carbon dioxide (CO₂), and sodium chloride (NaCl).
Mixture: A combination of two or more substances that are not chemically bonded and can be separated by physical means. Examples include air, saltwater, and a mixture of sand and water.

Chemical Formulas and Element Information

SO₂: This formula indicates a compound containing one sulfur atom and two oxygen atoms.

Element Symbols

Antimony: Sb
Gold: Au
Iron: Fe
Mercury: Hg
Potassium: K
Silver: Ag
Tin: Sn
Tungsten: W

Element Names from Symbols

Na: Sodium
Mg: Magnesium
Al: Aluminum
Si: Silicon
P: Phosphorus
Ar: Argon

Symbol Pair Differences

Co and Co (identical): Both represent the element cobalt, but one or two might represent different isotopes or different amounts of that certain element. Note: Need context or additional data for accurate interpretation.
Cs and Cs (identical): Both represent the element cesium. Note: Same as above, context required for isotopes.
Ho and H₂O: Ho represents the element Holmium, while H₂O represents water, a compound.
4P and P: 4P represents four phosphorus atoms; P represents one phosphorus atom.

Light Wavelengths

Light wavelengths range from approximately 0.0000004 cm to 0.0000007 cm.
In micrometers (µm): 0.4 µm to 0.7 µm
In nanometers (nm): 400 nm to 700 nm

Significant Figures

Determining the number of significant figures depends on the given numerical value, not the context.
Significant figures rules are required for accurate counting of the data.

Scientific Notation Conversion

11.98: 1.198 × 10¹
0.0046940: 4.6940 × 10⁻³
4,679,000: 4.679 × 10⁶

Subatomic Particles

Proton: Positively charged (+1)
Neutron: No charge (0)
Electron: Negatively charged (-1)

Atomic Symbols

Atom with 24 protons, 24 electrons, and 28 neutrons: ⁴⁸Ti

Atomic Structure and Numbers

Atom: Contains a nucleus with protons and neutrons, surrounded by electrons.
Atomic number: Number of protons in an atom (e.g., 53).
Mass number: Number of protons plus neutrons in an atom (e.g., 127).

More Atomic Symbols

Atom with 34 protons, 45 neutrons, and 34 electrons: ¹⁷⁹Se

Polyatomic Ions

Examples of polyatomic ions with -1, -2, and -3 charges:
- Nitrate (NO₃⁻): -1 charge
- Sulfate (SO₄²⁻): -2 charge
- Phosphate (PO₄³⁻): -3 charge

Periodic Table

Periods: Horizontal rows in the periodic table. Elements in the same period have increasing atomic numbers.
Groups: Vertical columns in the periodic table. Elements in the same group have similar chemical properties.

Elements in the Same Group

(b) Be, Mg, Ca: These elements are in the same group (Group 2).
Need additional data for the other element sets.

Additional Element Data

List of elements, and their symbols (H, He, Li, Be, B, C, N, O, F, Ne, ..., etc.)

Description

Test your knowledge on the definitions and characteristics of elements, compounds, and mixtures. This quiz covers various examples, chemical formulas, and element symbols essential for understanding basic chemistry concepts.