atoms elements and ions

Vocabulary flashcards covering core principles, atomic structure, elements, isotopes, mixtures, valence electrons, and chemical bonding.

Matter

Anything that has mass and occupies space.

Mass

The amount of matter in an object, whether living or nonliving.

Chemistry

The study of matter and its interactions.

Atom

The smallest unit of matter that still retains its original properties.

Proton

A positively charged ($+1$) subatomic particle located in the atomic nucleus with an approximate mass of $1.0073\,\text{amu}$.

Neutron

A neutral subatomic particle located in the atomic nucleus with a mass slightly larger than a proton ($\sim 1.0087\,\text{amu}$).

Electron

A negatively charged ($-1$) subatomic particle orbiting the atomic nucleus in electron shells with a mass of $\sim 0.00055\,\text{amu}$.

Element

A pure substance composed of only one type of atom that cannot be broken down into simpler substances by chemical means.

Atomic Number

The number of protons contained within the nucleus of an atom, which defines the element.

Major Elements

The four elements—Oxygen ($\sim 65\%$), Carbon ($\sim 18\%$), Hydrogen ($\sim 10\%$), and Nitrogen ($\sim 3\%$)—that make up approximately $96\%$ of the human body mass.

Mass Number

The sum of an atom's protons and neutrons.

Isotope

Atoms of the same element that have the same atomic number (number of protons) but different mass numbers due to a different number of neutrons.

Radioisotope

An unstable isotope that undergoes radioactive decay, emitting radiation as it breaks down.

Ion

An atom that has an electrical charge resulting from an unequal number of protons and electrons.

Cation

A positively charged ion formed when an atom loses one or more electrons ($\text{protons} > \text{electrons}$).

Anion

A negatively charged ion formed when an atom gains one or more electrons ($\text{protons} < \text{electrons}$).