Chapter 2: Life's Chemical Basis Vocabulary Flashcards

A complete set of vocabulary flashcards covering elements, atoms, isotopes, electron configuration, and chemical bonding based on Chapter 2 notes.

Element

A fundamental form of matter that cannot be broken down by normal means.

Four Most Common Elements in Living Organisms

1. Oxygen ($O$)
2. Hydrogen ($H$)
3. Carbon ($C$)
4. Nitrogen ($N$)

Periodic Table

Organizes elements based on their chemical properties; includes $92$ naturally found elements as well as man-made, unstable ones.

Atom

The smallest particle that retains the properties of an element.

Proton

A subatomic particle located in the nucleus with a positive ($+$) charge.

Neutron

A subatomic particle located in the nucleus with no charge ($0$).

Electron

A subatomic particle located around the nucleus with a negative charge that repels other electrons and is attracted to protons.

Atomic Number

The number of protons in an atom, which is identical for every atom of a given element (e.g., Hydrogen = $1$, Carbon = $6$).

Mass Number

The total sum of protons and neutrons in an atom ($\text{protons} + \text{neutrons}$).

Isotopes

Atoms of the same element with different numbers of neutrons and different mass numbers, such as Carbon-12 ($6$ protons + $6$ neutrons) and Carbon-14 ($6$ protons + $8$ neutrons).

Radioisotopes

Atoms with an unstable nucleus that release energy and particles, undergoing radioactive decay at a fixed rate called a half-life.

Half-life

The fixed rate at which a radioisotope undergoes radioactive decay.

Uses of Radioisotopes

Applications including medical imaging (such as PET scans), radiometric dating of rocks and fossils, radiation therapy, and biological tracers used to follow movement.

Orbital

A region around the nucleus where electrons move, capable of holding up to $2$ electrons. Orbitals closest to the nucleus have lower energy and fill first.

Shell Model

A representation of electron arrangement where the first shell has $1$ orbital (maximum $2$ electrons) and the second shell has $4$ orbitals (maximum $8$ electrons).

Electron Vacancies

Unfilled outer electron shells that make atoms more likely to react with other atoms.

Chemical Bond

A union between the electron structures of atoms.

Molecule

A chemical structure that can contain atoms of one element (e.g., $O_2$).

Compound

A chemical structure that contains atoms of more than one element (e.g., $H_2O$).

Three Important Biological Bonds

1. Ionic
2. Covalent
3. Hydrogen

Positive Ion

An atom that has lost electrons, resulting in a positive charge.

Negative Ion

An atom that has gained electrons, resulting in a negative charge.

Ionic Bond

A chemical bond formed by the transfer of electrons, occurring when one atom loses electrons and another atom gains them (e.g., $NaCl$).

Covalent Bond

A chemical bond formed when atoms share electrons to fill their outermost shell.

Single Covalent Bond

A covalent bond in which atoms share $1$ pair of electrons (e.g., $H-H$).

Double Covalent Bond

A covalent bond in which atoms share $2$ pairs of electrons (e.g., $O=O$).

Triple Covalent Bond

A covalent bond in which atoms share $3$ pairs of electrons.

Nonpolar Covalent Bond

A covalent bond in which electrons are shared equally between atoms (e.g., $H-H$).