Atoms and Elements - Vocabulary Flashcards (Video Notes)

Vocabulary flashcards covering core terms and concepts from the notes on atoms, elements, compounds, isotopes, and basic chemical notation.

Atom

The smallest unit of matter that retains the properties of an element; composed of a nucleus of protons and neutrons with electrons orbiting.

Element

A substance that cannot be broken down into simpler substances by chemical reactions.

Compound

A substance consisting of two or more elements in a fixed ratio; has emergent properties different from its constituent elements.

Emergent properties

New properties that appear when elements combine to form compounds and are not present in the elements alone.

Periodic table

A chart of the elements organized by properties, showing symbols and atomic numbers.

Atomic number

The number of protons in an atom; unique for each element.

Mass number

The total number of protons and neutrons in the nucleus of an atom.

Proton

Positively charged subatomic particle located in the nucleus.

Neutron

Electrically neutral subatomic particle located in the nucleus.

Electron

Negatively charged subatomic particle orbiting the nucleus.

Nucleus

The dense center of the atom containing protons and neutrons.

Isotope

Atoms of the same element (same protons) with different numbers of neutrons, giving different mass numbers.

Atomic mass

The sum of protons and neutrons in a single atom.

Atomic weight

The weighted average mass of the natural isotopes of an element.

Valence

The combining capacity of an atom, equal to the number of unpaired electrons in its outer shell.

Electron shell

An energy level around the nucleus where electrons reside.

Molecule

Two or more atoms bonded together to form a discrete unit.

Glucose (C6H12O6)

A molecule with 6 carbon, 12 hydrogen, and 6 oxygen atoms.

Sucrose (C12H22O11)

A molecule with 12 carbon, 22 hydrogen, and 11 oxygen atoms.

Ion

An atom that has gained or lost electrons, resulting in a net electrical charge.

Major elements in the human body

The most abundant elements by mass: Oxygen, Carbon, Hydrogen, and Nitrogen (with others like calcium and phosphorus in smaller amounts).

Iodine-123

A common isotope used in medicine with a half-life of 13.3 hours; used to study thyroid function.

Allotrope

Different structural forms of the same element (e.g., white phosphorus and red phosphorus).

Coefficient (in chemical formulas)

A number before a formula indicating how many molecules are present (e.g., 6CO2 = six molecules of carbon dioxide).