Life's Chemical Basis: Atoms, Isotopes, Electrons and Chemical Bonding

Flashcards about the chemical basis of life, atoms , isotopes, radioisotopes, and importance of electrons.

What are atoms?

Particles that are the building blocks of all substances.

What are the subatomic particles that make up atoms?

Protons (+), Electrons (-), Neutrons (no charge)

What defines an element's atomic number?

The number of protons.

What are isotopes?

Atoms of an element that differ in their number of neutrons.

What is the mass number of an isotope?

The total number of protons and neutrons in the nucleus.

What are radioisotopes?

Isotopes with an unstable nucleus that decay into predictable daughter elements at a predictable rate.

What is a tracer?

A molecule with a detectable label attached, used to track its path in a biological system.

What are orbitals?

Defined volumes of space around the atomic nucleus where electrons travel.

What happens if an atom’s outermost electron shell is full?

An element being chemically inactive because it is very stable.

What is an ion?

An atom that carries a charge due to an unequal number of protons and electrons.

What is a chemical bond?

An attractive force that arises between two atoms when their electrons interact.

What forms a molecule?

When two or more atoms of the same or different elements join in chemical bonds.

What are compounds?

Molecules that consist of two or more different elements in proportions that do not vary.

What forms a mixture?

When two or more types of molecules are intermingled in proportions that vary.

What are the three types of bonds are the most common in biological molecules?

Ionic, Covalent, and Hydrogen.

What is an ionic bond?

A strong mutual attraction of two oppositely charged ions.

What forms a covalent bond?

When two atoms share a pair of electrons.

What is a hydrogen bond?

An attraction between a hydrogen atom and an electronegative atom that are part of separate polar covalent bonds.

What is cohesion?

The tendency of molecules to stick together when a substance is under tension.

What is pH?

A measure of hydrogen ion concentration [H+] in a solution.

What is an acid?

Any substance that releases hydrogen ions into water.

What is a base?

Any substance that accepts hydrogen ions as it dissolves in water.

What is a salt?

A compound that dissolves easily in water and releases ions other than H+ and OH-.

What is a buffer system?

A set of chemicals, often a weak acid or base and its salt, that keeps the pH of a solution stable.