Atomic Structure & Mass Flashcards
What are the three subatomic particles that make up an atom?
Protons, neutrons, and electrons.
What is the charge and relative mass of a proton?
Charge: +1, Relative mass: ~1 atomic mass unit (amu).
What is the charge and relative mass of a neutron?
Charge: 0 (neutral), Relative mass: ~1 amu.
What is the charge and relative mass of an electron?
Charge: -1, Relative mass: ~1/1836 amu.
Where are protons and neutrons located in an atom?
In the nucleus.
Where are electrons located in an atom?
In orbitals around the nucleus.
What determines the atomic number of an element?
The number of protons in the nucleus.
What is the mass number (nucleon number) of an atom?
The sum of protons and neutrons in the nucleus.
What is an isotope?
Atoms of the same element with the same number of protons but different numbers of neutrons.
How do isotopes of the same element differ in properties?
They have the same chemical properties but different physical properties, such as mass and stability.
How is an element’s atomic symbol written?
Example: [ \, ^{A}_{Z}X ] where A = mass number, Z = atomic number, X = element symbol.
What does the atomic number represent?
The number of protons (and electrons in a neutral atom).
What does the mass number represent?
The total number of protons and neutrons in the nucleus.
What are stable isotopes?
Isotopes that do not undergo radioactive decay over time.
What are unstable isotopes?
Isotopes that decay over time, emitting radiation.
What is an energy level in an atom?
A discrete region where electrons exist at fixed distances from the nucleus.
What is the maximum number of electrons in the first four energy levels?
1st: 2, 2nd: 8, 3rd: 18, 4th: 32.
What is the Aufbau principle?
Electrons fill the lowest available energy levels first.
What is Hund’s rule?
Electrons occupy orbitals singly before pairing up.
What is the Pauli exclusion principle?
No two electrons in an atom can have the same set of four quantum numbers.
What are the four types of orbitals?
s, p, d, f.
How many electrons can each type of orbital hold?
s: 2, p: 6, d: 10, f: 14.
What is the electron configuration of oxygen (Z = 8)?
1s² 2s² 2p⁴.
How does electron configuration determine an element’s chemical properties?
Valence electrons determine reactivity and bonding behavior.
How is relative atomic mass (Ar) calculated?
Weighted average of isotope masses: [ Ar = \frac{(mass \times abundance) + (mass \times abundance)}{100} ]
Why isn’t the relative atomic mass always a whole number?
It accounts for the weighted average of all isotopes of the element.
What is the relative atomic mass of chlorine if Cl-35 (75%) and Cl-37 (25%) exist?
[ Ar = \frac{(35 \times 75) + (37 \times 25)}{100} = 35.5 ]
What is a flame test used for?
Identifying metal ions based on the color they emit in a flame.
What color does sodium produce in a flame test?
Yellow.
What color does copper produce in a flame test?
Blue-green.
How does the Bohr model explain atomic spectra?
Electrons absorb energy and jump to higher levels, then emit light as they fall back.
How does the Schrödinger model differ from the Bohr model?
It describes electron orbitals as probability clouds rather than fixed orbits.
What are the three main types of radioactive decay?
Alpha (α), Beta (β), Gamma (γ).
What is an alpha particle?
A helium nucleus (2 protons, 2 neutrons).
What is a beta particle?
A high-speed electron or positron.
What is gamma radiation?
High-energy electromagnetic waves.
What is a nuclear equation for alpha decay?
[ ^{238}{92}U \rightarrow ^{234}{90}Th + ^{4}_{2}He ]
What is a nuclear equation for beta decay?
[ ^{14}{6}C \rightarrow ^{14}{7}N + e^- ]
What is half-life?
The time required for half of a radioactive substance to decay.
Give an example of a human-made radioisotope.
Technetium-99m, used in medical imaging.
What is carbon-14 dating?
A method for determining the age of organic materials using the decay of carbon-14.
What is nuclear fission?
Splitting of a heavy nucleus into lighter nuclei, releasing energy.
What is nuclear fusion?
The combining of light nuclei into a heavier nucleus, releasing massive energy.
