Chemistry & Electricity of Matter

Matter

anything that takes up space and has mass (solid, liquid, or gas)

Elements

building blocks of matter and cannot be broken down by chemical means

Periodic Table of Elements

92 naturally occurring elements that make up the variety of living and non-living things in the world; other elements are synthetic

Columns in Periodic Table

arranged according to their properties and how they react to chemical reactions

C, H, O, and N

90% of the human body is made up of these elements

Atoms

the smallest unit of an element that still retains chemical and physical properties of that element; mostly made up of space

Protons

positively charged particles located in the nucleus (1 amu)

Neutrons

no charge, located in the nucleus (1 amu)

Electrons

negatively charged particles in orbit (energy shells) around the nucleus (0 amu, extremely small)

Compounds

atoms always try to fill energy shells for stability

Column Number

represents amount of electrons in outermost shell

Atomic Number

the number given to each element that indicates how many protons, and therefore, how many electrons an atom has when it is electrically neutral

Energy Shells

inner shell holds 2 electrons (lowest energy level); most other shells hold 8 electronsI

Isotopes

elements with same number of protons but differing number of neutrons

Mass

the quantity of matter; for an atom it is referred to as the atomic mass or mass number

Radiation

released (energy) as the more unstable isotope decays

Ions

charged particles (+ or -) formed when there is an imbalance of protons and electrons in an atom

Bonding

atoms combine to form molecules

Ionic Bonding

atoms take on an extra electron or give up an electron to form the bond to fill shells

Covalent Bonding

atoms share electrons instead of taking or giving up an electron to fill energy shells; these electrons spend part of their time in the outer shell of each atom

Structural Formulas

H — H

Molecular Formulas

H₂

Hydrogen Bonding

weak covalent bonds caused by the smaller H atom sharing its electron unequally with a much bigger atom such as O; molecule becomes polar; slightly more positive on the H side and more negative on the O side

Water

the most abundant molecule in living organisms (60-70% of total body weight)

pH Scale

used to indicate the acidity or basicity (alkalinity) of a solution

Acidic Solutions

high H ion concentration

Basic Solutions

low H ion concentration

Buffers

help keep the pH within normal limits; chemicals that take up excess H ions or excess OH ions

Carbonic acid

H₂CO₃; a weak acid that minimally dissociates

HCl

a strong acid