Who proposed the first atomic model with indivisible atoms?
John Dalton
Which atomic model introduced the concept of electrons orbiting the nucleus in energy levels or shells?
Niels Bohr
Which subatomic particle did J.J. Thomson discover?
Electron
What experiment led Ernest Rutherford to propose the nuclear model of the atom?
The Gold Foil Experiment
In Rutherford's atomic model, where is most of the atom's mass located?
In the nucleus
How many protons, neutrons, and electrons are in an atom with an atomic number of 12 and a mass number of 24?
12 protons, 12 neutrons, 12 electrons
What is the atomic mass of an element?
The weighted average of the masses of an element's isotopes.
Define Isotope
Atoms of the same element with different numbers of neutrons.
How do you calculate the number of neutrons in an atom?
Subtract the atomic number from the mass number.
What is an ion?
An atom or molecule with an unequal number of protons and electrons, resulting in a charge.
In the periodic table, which group contains the alkali metals?
Group 1 (I A)
What is the significance of the group number on the periodic table?
It indicates the number of valence electrons in the elements of that group.
Which element is always found in Group 18 (VIII A) of the periodic table?
Noble gases (e.g., helium, neon, argon)
What are the elements found in Group 17 (VII A) called?
Halogens (e.g., fluorine, chlorine)
Name the transition metals found in the middle of the periodic table.
Elements from groups 3 to 12
What do elements in the same period of the periodic table have in common?
They have the same number of electron shells.
