Lab 2: Atoms, Molecules & Compounds

Vocabulary practice flashcards covering fundamental chemistry concepts, atomic structure, periodic table organization, bonding types, and molecular shapes from Lab 2 (BIO-102).

Matter

Anything that takes up space and has mass, existing as a solid, liquid, or gas.

Elements

Substances that cannot be broken down into simpler substances by ordinary chemical means.

Naturally Occurring Elements

The $92$ elements that serve as the fundamental building blocks of all matter.

Major Elements of Organisms

The six elements that make up $95\%$ of organisms by weight: oxygen ($\text{O}$), carbon ($\text{C}$), hydrogen ($\text{H}$), nitrogen ($\text{N}$), phosphorus ($\text{P}$), and sulfur ($\text{S}$).

Atom

The smallest part of an element that displays the properties of that element.

Protons

Positively charged subatomic particles located in the nucleus with an electric charge of $+1$ and an atomic mass unit (AMU) of $1$.

Neutrons

Uncharged subatomic particles located in the nucleus with an electric charge of $0$ and an atomic mass unit (AMU) of $1$.

Electrons

Negatively charged subatomic particles located in the electron shell with an electric charge of $-1$ and an atomic mass unit (AMU) of $0$.

Atomic Number

The number of protons found in the nucleus of an atom.

Mass Number

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

Periodicity

The phenomenon where certain chemical and physical properties recur among elements in the periodic table.

Groups

The vertical columns on the periodic table that group elements by recurring characteristics.

Periods

The horizontal rows of elements on the periodic table.

Isotopes

Atoms of the same element that have different numbers of neutrons.

Radioactive Isotopes

Unstable isotopes that emit various types of energy as they decay.

Electron Shells (Electron Orbitals)

The specific energy levels at which electrons orbit the nucleus; the first shell holds up to two electrons, and subsequent shells can hold up to eight.

Octet Rule

The rule stating that an atom's valence shell is stable when it contains $8$ electrons ($8e^-$).

Molecules

Chemical units formed when two or more atoms bond together (for example, $\text{O}_2$).

Compounds

Substances formed when two or more different elements bond together (for example, $\text{H}_2\text{O}$).

Ions

Charged atoms that form when electrons are transferred from one atom to another.

Ionic Bond

The attraction between oppositely charged ions that holds ionic compounds together.

Covalent Bond

A chemical bond formed when atoms share electrons so each atom achieves a complete outer orbital.

Single Covalent Bond

A covalent bond that results from the sharing of one pair of electrons between two atoms.

Double Covalent Bond

A covalent bond that results from the sharing of two pairs of electrons between two atoms.

Tetrahedral Shape

The three-dimensional geometry adopted by five-atom molecules such as methane ($\text{CH}_4$), characterized by bond angles of $109^\circ$.

Electronegativity

The attraction of an atom for electrons participating in a covalent bond.

Nonpolar Covalent Bond

A covalent bond that occurs when the sharing of electrons between two atoms is fairly equal.

Polar Covalent Bond

A covalent bond that occurs when electrons are shared unequally between atoms due to differences in electronegativity.

Hydrogen Bond

A weak attraction between a partially negative ($-$) oxygen atom in one molecule and a partially positive ($+$) hydrogen atom in another molecule.