Chapter 2, Lesson 1: Atoms, Ions, and Molecules

Flashcards from Chapter 2, Lesson 1 of McGraw Hill Anatomy and Physiology, Ninth Edition, by Kenneth S. Saladin.

Element

The simplest form of matter to have unique chemical properties

Atomic number

The number of protons in the nucleus; the periodic table is arranged by these and is accompanied by a symbol

Oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus

The six elements that make up 98.5% of a person’s body weight alongside small amounts of trace elements

Minerals

Inorganic elements extracted from soil by plants and passed up food chain to humans; they constitute about 4% of body weight and are important for body structure and enzyme function

Electrolytes

Mineral salts needed for nerve and muscle function; they ionize and conduct electricity in water

Neils Bohr

Scientist who proposed the planetary model of the atomic structure in 1913

Nucleus

The center of the atom

Protons

A particle located in the nucleus with a positive charge and mass of 1 amu

Neutrons

A particle located in the nucleus with no charge and mass of 1 amu

Atomic mass

Calculated by adding protons and neutrons

Electrons

Particles with a single negative charge and very low mass that exist in a cloud around the nucleus; they maintain neutrality to counter the positive protons

Valence electrons

Electrons in the outermost shell and determine the chemical bonding properties of an atom

Isotopes

Varieties of an element that differ in neutrons; they are heavier due to the neutrons but have the same number of valence electrons

Atomic weight

A weighted average of the commonality of isotopic weights

Radioisotopes

Unstable isotopes that decay and give off radiation

Free radicals

Electrons that are ejected from radioisotopes which can cause cancer and destroy molecules

Physical half-life

Time required for 50% of a radioisotope to become stable

Biological half-life

Time required for 50% of a radioisotope to disappear from the body

Sievert (Sv)

Unit of radiation dosage

5 Sv

Fatal dosage of radiation

50 mSv

Standard acceptable exposure per year

Background radiation

Comes from natural sources like radon gas and cosmic rays; transfers about 2.4 mSv per year

Artifical sources of radiation

Comes from X-rays, color TVs, etc.; transfers about 0.6 mSv per year

Madame Marie Curie

First woman to recieve a Nobel Prize and discovered, created treatment for, and died of radioactivity

Ion

A charged particle with an unequal number of protons and electrons

Ionization

The transfer of electrons from one atom to another

Anion

Particle with a net negative charge due to gain of electrons

Cation

Particle with a net positive charge due to loss of electrons

Free radicals

Short-lived particles with an unusual number of electrons, they are produced by metabolic reactions, radiation, and chemicals; may destroy molecules and cause aging and cancer

Antioxidants

Chemicals that neutralize free radicals

Molecule

Particle composed of two or more atoms united by a chemical bond

Compound

Molecule composed of two or more different elements

Molecular formula

Identifies elements and how many of each are present

Structural formula

Identifies location of each atom

Isomer

Molecules with identical formulae but different arrangements of atoms

Molecular weight

Calculated by finding the sum of the atomic weights of each atom

Chemical bonds

Holds atoms together within a molecule; examples include ionic, covalent, hydrogen, and van der Walls forces

Ionic bond

Attraction of a cation to an anion by transferring an electron, but is easily broken by water

Covalent bond

A bond where atoms share one or more pairs of electrons

Nonpolar covalent bond

Electrons are shared equally between atoms, symmetrical

Polar covalent bond

Electrons are shared unequally, nonsymmetrical

Hydrogen bond

Weak attraction between a slightly positive hydrogen atom in one molecule and a slightly negative oxygen or nitrogen in another; affects cohesion and adhesion in water and DNA molecular structure

Van der Walls forces

Very weak and brief attractions between neutral atoms which create polar bonds