Ch 13: Inside the Atom

Study Notes

Sub-atomic Particles

Protons:
- Located in the nucleus of the atom
- Charge: +1 (positive)
Neutrons:
- Also found in the nucleus
- Charge: Neutral (no electric charge)
Electrons:
- Orbit around the nucleus in specific energy levels or shells
- Charge: -1 (negative)

Atomic Number and Mass Number

Atomic Number (Z):
- Represents the number of protons in the nucleus
- Identifies a chemical element uniquely (e.g., Carbon has Z = 6)
Mass Number (A):
- Total number of protons and neutrons in the nucleus
- Calculated using the formula: A = Z + N (where N is the number of neutrons)

Calculating Protons, Neutrons, and Electrons

Number of Protons (p): Equal to the atomic number (Z)
Number of Neutrons (n): Calculated by n = A - Z
Number of Electrons (e): Equal to the number of protons in a neutral atom

Valence Electrons and Electron Configuration

Argon (Ar):
- Atomic number: 18
- Electron configuration: 2, 8, 8
- Valence electrons: 8
Aluminum (Al):
- Atomic number: 13
- Electron configuration: 2, 8, 3
- Valence electrons: 3
Oxygen (O):
- Atomic number: 8
- Electron configuration: 2, 6
- Valence electrons: 6

Atomic Structure from Bohr’s Model

Element with Z = 20:
- Mass number (A): 40
- Protons: 20
- Neutrons: 20
- Electrons: 20
Element with Z = 11:
- Mass number (A): 23
- Protons: 11
- Neutrons: 12
- Electrons: 11

Distinctions Between Atoms, Ions, Molecules, Compounds, and Mixtures

Atoms:
- Smallest unit of an element retaining its chemical properties
- Example: Hydrogen (H), Carbon (C)
Molecules:
- Two or more atoms bonded together
- Same element example: Oxygen (O₂)
- Different elements example: Water (H₂O)
Ions:
- Atoms or molecules with a net electrical charge due to loss or gain of electrons
- Cations: Positively charged (e.g., Na⁺)
- Anions: Negatively charged (e.g., Cl⁻)
Compounds:
- Formed by chemically bonded different elements
- Unique properties compared to individual elements
- Example: Sodium chloride (NaCl), Carbon dioxide (CO₂)
Mixtures:
- Combination of two or more substances that are not chemically bonded
- Components retain individual properties
- Example: Saltwater (homogeneous), Sand and iron filings (heterogeneous)

Writing Chemical Formulae

Atoms:
- H₂O: Two hydrogen atoms + One oxygen atom
- CO₂: One carbon atom + Two oxygen atoms
Simple Ionic Compounds:
- Ca²⁺ + Cl⁻ → CaCl₂
- Mg²⁺ + Br⁻ → MgBr₂
- Al³⁺ + S²⁻ → Al₂S₃
Polyatomic Ions:
- Interaction involves complex ions with multiple atoms that carry a charge.

Description

Explore the fundamental components of an atom in this quiz. You'll identify the three sub-atomic particles—protons, neutrons, and electrons—along with their locations and charges. Test your understanding of atomic structure now!