Chem 110 Unit 1 Test Review Chapter 2

Proton

Positively charged (+1) subatomic particle located in the nucleus.

Neutron

Neutral (0) subatomic particle located in the nucleus.

Electron

Negatively charged (−1) subatomic particle found in the electron cloud surrounding the nucleus.

Atomic number

Number of protons in an atom's nucleus. Determines the identity of the element.

What determines an atom's charge?

The difference between the number of protons and electrons.

Neutral atom

An atom with equal numbers of protons and electrons, resulting in no overall charge.Cation

Cation

Positively charged ion formed when an atom loses electrons.

Anion

Negatively charged ion formed when an atom gains electrons.

Atomic mass

Weighted average mass of an element's naturally occurring isotopes, measured in atomic mass units (amu).

Mass number

Total number of protons and neutrons in an atom's nucleus.

Atomic mass unit (amu)

Unit used to express atomic and molecular masses; approximately the mass of one proton or neutron.

Difference between atomic mass and mass number

Atomic mass is the weighted average of an element's isotopes, while mass number is the total protons and neutrons in one specific atom.

How do you calculate mass number?

Mass number = protons + neutrons.

Isotope

Atoms of the same element with the same number of protons but different numbers of neutrons.

What distinguishes isotopes of the same element?

Different numbers of neutrons and different mass numbers.

Do isotopes of the same element have the same atomic number?

Yes. They have the same number of protons.

Radioisotope

An unstable isotope that undergoes radioactive decay and emits radiation.

Stable isotope

An isotope that does not spontaneously undergo radioactive decay.

How are isotopes named?

Element name followed by mass number, such as carbon-14 or uranium-238.

Isotope notation

Written as ᴬZX, where A = mass number, Z = atomic number, and X = chemical symbol.

Nuclear radiation

Particles or energy emitted from an unstable atomic nucleus.

Radioactive

Describes a substance containing unstable nuclei that spontaneously emit radiation.

Radioactive decay

Spontaneous transformation of an unstable nucleus into a more stable nucleus, releasing radiation.

Radioactivity

The process of spontaneous nuclear decay or the rate at which radioactive nuclei decay.

Radioisotope

An isotope with an unstable nucleus that undergoes radioactive decay.

Does radioactive decay involve the nucleus or electrons?

The nucleus.

Can radioactive decay change one element into another?

Yes. Some types of radioactive decay change the number of protons, producing a different element.

Alpha particle (α)

Particle consisting of 2 protons and 2 neutrons, with a +2 charge.

Beta particle (β⁻)

High-energy electron emitted from the nucleus during radioactive decay, with a −1 charge.

Gamma ray (γ)

High-energy electromagnetic radiation emitted from an unstable nucleus; has no mass or charge.

Becquerel (Bq)

SI unit of radioactivity equal to one nuclear decay per second.

Curie (Ci)

Unit of radioactivity equal to 3.7 × 10¹⁰ nuclear decays per second: 1 Ci = 3.7 × 10¹⁰ Bq.