History
Who was the first to propose that matter was made up of indivisible particles called “atoms”?
Dalton
What subatomic particle has a positive charge?
Proton
Which is the most abundant carbon?
C-12
If an atom has an equal number of protons and electrons, what is its net charge?
NEUTRAL
What is the atomic number of an element?
Number of protons
Which atomic model described the atom as a positive sphere with embedded electrons, resembling a "pudding with raisins"?
Thomson model
What is the name of a subatomic particle without an electrical charge?
Neutron
What is the difference between the atomic number and the mass number of an atom?
Atomic numbre: protons
Mass: p+n
An atom has 12 protons, 12 neutrons, and 12 electrons. What is its atomic number and mass number?
Atomic number 12
Mass number 24
Where are protons and neutrons located in an atom?
At nucleus
What main contribution did Rutherford's gold foil experiment make?
Discovery of nucleus positively charged
What subatomic particle moves around the nucleus in orbitals?
Electrons
Carbon has two isotopes: C-12 and C-14. If an atom has 6 protons and 8 neutrons, what isotope is it?
C-14
An ion has 17 protons and 18 electrons. What is its net charge?
-1
What differentiates an oxygen atom from a hydrogen atom?
Number of protons, mass, atomic number
Which scientists proposed the quantum mechanical model of the atom?
Erwin Schrödinger (1926): formulated the wave equation, which mathematically describes the behavior of the electron as a probability function.
Werner Heisenberg (1927): Uncertainty principle.
A calcium ion has 20 protons, 18 electrons, and 20 neutrons. What is its net charge and mass number?
Mass: 40
Charge: +2
What are atoms that have the same number of protons but different numbers of neutrons called?
Isotopes
A sodium ion (Na⁺) has 11 protons and 10 electrons. How many neutrons does it have if its mass number is 23?
12 neutrons
What is the Carbon-14 isotope primarily used for in science?
Carbon-14 (C-14) is primarily used to determine the age of organic materials using the radiocarbon dating technique.
What is the fundamental difference between the Bohr model and the quantum mechanical model?
Bohr: electrons in fixed orbits (planetary model).
Quantum mechanics: electrons in orbitals (probability clouds), without defined trajectories.
Why don't electrons contribute significantly to an atom's mass?
Because electrons are extremely light compared to protons and neutrons
Why do isotopes of the same element have almost identical chemical properties, but can behave very differently in nuclear processes?
Isotopes of the same element have the same number of protons and electrons, so they retain virtually the same chemical properties and react similarly in bonds and chemical reactions. However, they differ in the number of neutrons, which affects their atomic mass and, above all, their nuclear stability.
An iron ion Fe+3 has 26 protons and 30 neutrons.
a) How many electrons does this ion have?
b) What is its mass number?
c) What is its net charge?
23 electrons, a mass number of 56 and a net charge of +3.
What is the difference between a cation and an anion in terms of subatomic particles?
The number of protons never changes, only the number of electrons changes when ions form.
Anion gains electrons
Cation looses electrons