The maximum number of electrons that can occupy a shell of number n is given by the formula ___ .

True or False: The mass of an electron is approximately equal to 1/1840 times the mass of a neutron.

An atom is electrically neutral because it has an equal number of ___ and ___.

Riddle: I am found in the center of an atom, made of protons and neutrons, I am very small yet hold great power. What am I?

The nucleus

The size of an atom is typically on the order of ___ meters.

10^-10

Fill in the blank: The total number of nucleons in the nucleus is called the ___ of the element.

Mass number

What determines the size of an atom?

Riddle: I am a particle with no charge, yet I am essential to the nucleus. Without me, the atom would be incomplete. What am I?

What distinguishes stable isotopes from unstable isotopes?

Stable isotopes have equal neutrons and protons.

• Stable isotopes do not decay.

• Unstable isotopes undergo decay.

• Neutron-proton ratio affects stability.

Riddle: I am an element's twin, with the same number of protons, but my neutrons differ. What am I?

An isotope.

How many neutrons does deuterium have compared to protium?

Deuterium has one neutron, while protium has no neutrons.

True or False: Hydrogen has three isotopes: protium, deuterium, and tritium.

True.

The number of nucleons in isobars is represented by ___ and their atomic number is represented by ___.

A (mass number) and Z (atomic number), respectively.

What are the three types of radiation emitted during radioactive decay, and how can they be distinguished?

Three types of radiation are α, β, γ.

• Alpha particles: positively charged.

• Beta particles: negatively charged.

• Gamma rays: uncharged radiation.

Fill in the blank: The phenomenon of radioactivity is a ___ phenomenon.

Nuclear