Chapter 2: The Molecules of Cells - Basic Chemistry & Molecules

Vocabulary flashcards covering basic atomic structure, elements, isotopes, radiation, and chemical bonding from Sections 2.1 and 2.2 of Chapter 2.

Matter

Anything that takes up space and has mass, consisting of chemical elements.

Elements

Substances composed of atoms that serve as the building blocks of all matter, with 92 naturally occurring elements in total.

CHNOPS

An acronym standing for the most significant elements found in all organisms: carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur.

Protons

Subatomic particles located in the nucleus of an atom that have a positive charge (+1) and an atomic mass unit of 1.

Neutrons

Uncharged subatomic particles located in the nucleus of an atom with an atomic mass unit of 1.

Electrons

Subatomic particles located in the electron shell surrounding the nucleus with a negative charge (-1) and an atomic mass unit of 0.

Atomic Number

The total number of protons in the nucleus of an atom, which also indicates the number of electrons in electrically neutral atoms.

Mass Number

The total sum of the number of protons and neutrons in an atom, represented by the formula $\text{mass number} = \text{number of protons} + \text{number of neutrons}$.

Isotopes

Atoms of the same element that have the same number of protons but different numbers of neutrons, resulting in different mass numbers.

Radioactive Isotopes

Unstable isotopes that change over time into stable isotopes by releasing energy in the form of rays and subatomic particles.

Compound

A substance formed when atoms of two or more different elements bond together.

Molecule

A group of two or more atoms bonded together covalently, which can consist of the same element or different elements.

Ions

Charged particles that form when atoms lose or gain one or more electrons to achieve a completed outer orbital.

Ionic Bond

An attraction holding ionic compounds together, formed between oppositely charged ions created by the transfer of electrons.

Covalent Bond

A chemical bond formed when two atoms share one or more pairs of electrons.

Nonpolar Covalent Bond

A covalent bond in which the sharing of electrons between atoms is equal.

Electronegativity

The measure of an atom's attraction or pull for shared electrons in a covalent bond.

Polar Covalent Bond

A covalent bond in which electrons are shared unequally between atoms due to differences in electronegativity, creating slight partial charges.

Hydrogen Bond

A weak attraction between a slightly positive hydrogen atom and a slightly negative oxygen or nitrogen atom within the same or a different molecule.