General Biology I - Chapter 2: The Chemical Context of Life

Flashcards from General Biology I lecture notes focusing on the chemical context of life.

What is matter?

Anything that takes up space and has mass.

What is an element?

A substance that cannot be broken down to other substances by chemical reactions.

What is a compound?

A substance consisting of two or more elements in a fixed ratio.

What four elements make up approximately 96% of living matter?

Carbon, hydrogen, oxygen, and nitrogen.

What are trace elements?

Elements required by an organism in minute quantities.

What is an atom?

The smallest unit of matter that still retains the properties of an element.

What are the relevant subatomic particles?

Neutrons, protons, and electrons.

What is an element's atomic number?

The number of protons in its nucleus.

What is an element's mass number?

The sum of protons plus neutrons in the nucleus.

What are isotopes?

Two atoms of an element that differ in the number of neutrons.

What is energy?

The capacity to cause change.

What is potential energy?

The energy that matter has because of its location or structure.

What is an energy level or electron shell?

An electron's state of potential energy.

What are valence electrons?

Electrons in the outermost shell, or valence shell.

What is an orbital?

The three-dimensional space where an electron is found 90% of the time.

What is a covalent bond?

The sharing of a pair of valence electrons by two atoms.

What is a molecule?

Two or more atoms held together by covalent bonds.

What is electronegativity?

An atom's attraction for the electrons in a covalent bond.

What defines a nonpolar covalent bond?

The atoms share the electron equally.

What defines a polar covalent bond?

One atom is more electronegative, and the atoms do not share the electron equally.

What is an ion?

A charged atom or molecule.

What is a cation?

A positively charged ion.

What is an anion?

A negatively charged ion.

What is an ionic bond?

An attraction between an anion and a cation.

What are ionic compounds or salts?

Compounds formed by ionic bonds.

What is a hydrogen bond?

Forms when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom.

What are Van der Waals interactions?

Attractions between molecules that are close together as a result of these charges.

What are chemical reactions?

The making and breaking of chemical bonds.

What are reactants?

The starting molecules of a chemical reaction.

What are products?

The final molecules of a chemical reaction.

What defines chemical equilibrium?

Reached when the forward and reverse reaction rates are equal.