REG Chemistry Midterm Review

Front

What is the nucleus of an atom made of?

Back

The nucleus of an atom is made of protons and neutrons.

Front

What happens to atomic radius as you move down a group in the periodic table?

Back

Atomic radius increases because you add more and more shells (energy levels).

Front

What is the half-life of technetium-99?

Back

The half-life of technetium-99 is 6.0 hours.

Front

How much technetium-99 remains after 18 hours if 100.0 mg were injected?

Back

12.5 mg remains after 18 hours.

Front

What happens to atomic radius as you move across the periodic table from left to right?

Back

The atomic radius decreases because the number of protons increases, so attraction to electrons increases.

Front

What is the atomic mass of an atom equal to?

Back

The atomic mass of an atom is equal to the number of protons plus the number of neutrons.

Front

Define atomic radius.

Back

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

Front

What is the significance of protons in an atom?

Back

Protons determine the atomic number and identity of an element.

Front

What role do neutrons play in an atom?

Back

Neutrons contribute to the atomic mass and stability of the nucleus.

Front

Explain why atomic radius increases down a group.

Back

Atomic radius increases down a group due to the addition of energy levels, which increases the distance between the nucleus and the outermost electrons.