1st Semester final review #1: At. Theory and Radioactivity

Front

What is the atomic radius of a magnesium atom compared to a sodium atom?

Back

The atomic radius of a magnesium atom is smaller than that of a sodium atom due to a larger nuclear charge.

Front

What is the historical sequence leading to the modern model of the atom?

Back

1. The atom is a hard sphere. 2. Most of the atom is empty space. 3. Electrons exist in orbitals outside the nucleus.

Front

Back

The equation is incomplete; additional products or reactants need to be specified.

Front

Can fusion reactions be used to produce energy in nuclear reactors on Earth?

Back

No, fusion reactions cannot be used to produce energy in reactors on Earth.

Front

How does an atom in the ground state become excited?

Back

An atom becomes excited by absorbing energy, causing one or more electrons to move to a higher electron shell.

Front

What is the definition of atomic radius?

Back

Atomic radius is the distance from the nucleus of an atom to the outermost shell of electrons.

Front

What is nuclear charge?

Back

Nuclear charge is the total charge of the nucleus, determined by the number of protons.

Front

What is the difference between ground state and excited state of an atom?

Back

In the ground state, electrons are in the lowest energy levels; in the excited state, electrons have absorbed energy and moved to higher energy levels.

Front

What is the significance of the electron cloud model?

Back

The electron cloud model describes the regions around the nucleus where electrons are likely to be found, emphasizing that their exact positions cannot be determined.

Front

What is the principle of conservation of mass in nuclear reactions?

Back

The principle states that mass is neither created nor destroyed in a chemical reaction, including nuclear reactions.