Chapter 2 The Chemical Basis of Life Lecture Outline

Flashcards covering vocabulary terms from the Chemical Basis of Life lecture notes.

Matter

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

Element

A substance that cannot be broken down into another substance by ordinary chemical means and differ in their chemical and physical properties.

Most Abundant Elements in Living Organisms

Carbon, hydrogen, nitrogen, oxygen, sulfur, and phosphorus.

Four elements that make up about 96% of the body weight of most living organisms

Carbon, Hydrogen, oxygen, and Nitrogen

Atom

Smallest unit of matter that retains all the element's chemical properties.

Nucleus

The atom's center and contains protons and neutrons.

Neutrons

No electrical charge, mass 1 (atomic mass unit- amu).

Protons

Positive charge, mass 1 (amu ).

Electrons

Negative charge, mass 0 (amu).

Mass number of an atom

Is equal to sum of protons and neutrons, which are similar in mass.

Mass

The amount of matter in an object.

Weight

A measure of the gravitational force exerted on an object.

Atomic number

The number of protons within the nucleus of an atom.

Atomic mass

The average value of mass number for all isotopes of an atom.

Atomic symbol

Name of the atom or element.

Periodic table

Displays the elements’ chemical and physical characteristics and groups elements that share certain chemical properties with other elements.

Isotopes

Atoms of the same element that differ in the number of neutrons.

Radioactive isotopes

Nucleus with excess neutrons can be unstable and may decay, emitting radiation.

Positron Emission Tomography (PET) scan

Tracer use to determine the comparative activity of tissue.

Electron shells or energy levels

The orbits that electrons move in.

OCTET RULE

States, except for the innermost shell, that atoms are more stable energetically when they have eight electrons in their valence shell, the outermost electron shell.

Valence shell of an atom

The outermost electron shell.

Cations

Positive ions that form by losing electrons.

Anions

Negative ions form by gaining electrons.

Molecular formula

Simply shows number of atoms involved.

Reactants

The substances used in the beginning of a chemical reaction.

Products

The substances at the end of the reaction.

Balanced chemical equation

Each element’s number of atoms is the same on each side of the equation.

Molecule

When two or more atoms chemically bond with each other, the resultant chemical structure.

Compound

A molecule made up of atoms of 2 or more different elements joined by chemical bonds.

Chemical Bond

The energy or forces holding two atoms together.

Ionic bonds

Involves the transfer of electrons and attraction between opposite charges.

Covalent bonds

Sharing electrons to complete outer shell.

Hydrogen Bonds

The force that is generated by the attraction of opposite partial electrical charges.

Salts

Solid substances formed by ionic bonds that usually dissociate into individual ions in water.

Electrolytes

Ions necessary for nerve impulse conduction, muscle contractions, and water balance.

Structural formula

Uses straight lines to indicate 1 pair of shared electrons.

Polar Covalent Bonds

Atoms unequally share the electrons and are attracted more to one nucleus than the other.

Nonpolar covalent bonds

Form between two atoms of the same element or between different elements that share electrons equally.

Hydrogen bonds

Provide many of the critical, life- sustaining properties of water and stabilize the structures of proteins and DNA, the building block of cells.

Van der Waals interactions

Weak attractions or interactions between molecules.