Atomic Structure Quiz

Atomic Number

• Defines the number of protons in an atom's nucleus.
• All atoms of a given element have the same atomic number.
• Represented by the symbol 'Z'.
• Found on the periodic table above or below the element symbol.

Mass Number

• Defines the total number of protons and neutrons in an atom's nucleus.
• Represented by the symbol 'A'.
• Calculated using the formula: A = Protons + Neutrons
• Not necessarily the same for all atoms of a given element, leading to isotopes.

Isotopes

• Atoms of the same element with the same number of protons but different numbers of neutrons.
• Have different mass numbers.
• Example: Carbon-12 and Carbon-13.

Subatomic Particles

• Particles smaller than an atom.
• Include protons, neutrons, and electrons.

Protons

• Positively charged (+1).
• Found in the nucleus.
• Have a mass of 1 atomic mass unit (amu).

Neutrons

• Neutrally charged (0).
• Found in the nucleus.
• Have a mass of approximately 1 amu.

Electrons

• Negatively charged (-1).
• Found in orbitals outside the nucleus.
• Have a negligible mass (almost 0 amu).

Finding Atomic Number

• Found on the periodic table by looking at the whole number above or below the element symbol.
• Example: Carbon has an atomic number of 6, represented as Z = 6.

Finding Mass Number

• Cannot be found directly on the periodic table.
• Requires knowledge of the number of neutrons in a specific isotope of the element.
• Example: Silicon-29 has 14 protons and 15 neutrons, resulting in a mass number of 29.

Representation of Elements

• Can be represented by the element's mass number, e.g., Oxygen-16.
• Can be represented visually with atomic number as a subscript and mass number as a superscript, e.g., ¹⁶₈O.

Atomic Number vs. Mass Number

• Relationship: Both consider the number of protons in the nucleus.
• Differences:
  • Atomic number is a fundamental property of an element, defining its identity, while mass number varies for isotopes.
  • Atomic number is always the same for all atoms of an element, while mass number can vary based on the number of neutrons.

Mass Number vs. Atomic Mass

• Mass number: Represents the number of protons and neutrons in a single atom.
• Atomic mass: Weighted average of mass numbers of all atoms of an element, considering the abundance of different isotopes.
• Atomic mass is listed on the periodic table next to the element symbol.

Isobars

• Atoms of different elements with the same mass number.
• Have different numbers of protons and neutrons that add up to the same total mass.
• Example: Carbon-14 and Oxygen-14.