Questions and Answers
What is the charge of a neutron?
If an atom has an atomic number of 8 and a mass number of 16, how many neutrons does it contain?
Where are electrons located in an atom?
What defines the atomic number of an element?
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What is the mass number of an atom with 15 protons and 10 neutrons?
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How many valence electrons does aluminum (Al) have?
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Which of the following correctly defines an ion?
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What is the mass number of an element with 20 protons and 20 neutrons?
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What type of chemical formula results from combining calcium ion (Ca²⁺) and chloride ion (Cl⁻)?
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Which of the following correctly distinguishes a compound from a mixture?
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Which of the following molecules contains more than one type of atom?
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What is the electron configuration for argon (Ar)?
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In Bohr's model, which statement is true regarding atomic structure?
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Study Notes
Sub-atomic Particles
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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
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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
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Argon (Ar):
- Atomic number: 18
- Electron configuration: 2, 8, 8
- Valence electrons: 8
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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
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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
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Atoms:
- Smallest unit of an element retaining its chemical properties
- Example: Hydrogen (H), Carbon (C)
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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⁻)
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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
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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.
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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!
