Science Chapter 9: Atoms, Isotopes, and the Periodic Table Vocabulary

Vocabulary flashcards covering key terms, definitions, periodic trends, subatomic particles, and atomic properties from Science Chapter 9.

Valence electrons

The electrons that most affect an atom's chemical properties.

Isotopes

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

Atomic number

The number of protons in an element's atom.

Electron cloud

The region of an atom that occupies most of its volume.

Electron

The subatomic particle that has the smallest mass.

Atomic nucleus

The structure located at the center of every atom, containing protons and neutrons.

Halogens

The group on the periodic table to which fluorine, chlorine, and bromine belong.

Atomic radius trend across a period

The general decrease in atomic radius from left to right across a period.

Atomic radius trend down a group

The general increase in atomic radius going down a group.

Period 3 atomic radius ranking

The ranking of Period 3 atoms from largest to smallest atomic radius: $\text{Na} > \text{Al} > \text{Si} > \text{S} > \text{Ar}$.

Mass number

The total number of protons and neutrons in an isotope.

Carbon-13

The isotope that has 6 protons and 7 neutrons.

Periodic table ordering

The arrangement of elements in order of increasing atomic number.

Transition metals

A set of common metallic elements that includes tungsten, platinum, and iron.

Metals

The category that comprises most of the known elements on the periodic table.

Noble gas shell model

A theoretical model that helps explain periodic table organization.

Subatomic particle mass order

The order of subatomic particles from least to greatest mass: electron, proton, neutron.

Carbon-12 sample atom count

A $1\,\text{g}$ sample of carbon-12 has the most atoms compared to equal $1\,\text{g}$ samples of carbon-13 and uranium-238 because carbon atoms have less mass.

Atom size ranking (Cu, Ne, H)

The size order of atoms according to the course model from largest to smallest: $\text{Cu} > \text{Ne} > \text{H}$.

Aluminum (Al)

The element that tends to lose the most valence electrons in simple bonding when compared to lithium (Li), magnesium (Mg), or boron (B).

Bromine isotopes

Two equally common isotopes with mass numbers 79 and 81 that produce an average atomic mass of about $80\,\text{amu}$.

Metalloid

An element that exhibits properties between metals and nonmetals, represented by silicon in the provided list.

Polonium (Po)

The element that has the largest atomic radius among oxygen (O), sulfur (S), selenium (Se), tellurium (Te), and polonium (Po).