Basic Chemistry. General Biology. Matter – Atoms and Elements. Living and nonliving things are all made up of matter . Matter is anything that has mass and takes up space. Made of particles called atoms . An atom is the most basic unit of matter.
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There are four main elements in the molecules that make up the bulk of living organisms.
Online Periodic Table: www.webelements.com
The arrangement of electrons determines how the atom behaves.
Atoms have no charge because the number of protons and the number of electrons is equal. (=neutral).
We will only deal with elements with atomic numbers between 1 and 20. For atoms with higher atomic numbers, the rules are a little more detailed.
Column 1: Very reactive. Tend to lose 1 electron atom determines its
Column 2: Tend to lose 2 electrons
Column 3: Tend to lose 3 electrons
Column 4: Tend to share electrons
Column 5: Tend to gain 3 electrons
Column 6: Tend to gain 2 electrons
Column 7: Very reactive. Tend to gain 1 electron
Column 8: NONREACTIVE – have either 2 or 8 electrons in valence.
a. Covalent bonds
b. Ionic bonds
Covalent Bonds atom determines its
involve sharing electron(s) between two or more atoms.
a molecule is a grouping of atoms which have covalently bonded together.
covalently bonded molecules have no overall charge – they are neutral.COVALENT BONDS
Coefficient: How many of that molecule
Subscript: the number of atoms of that element in the molecule
Reactants: starting substances
Products: ending substances
Energy is used to break bonds in the reactant(s). Then atoms interact and rearrange, and energy is released when new bonds are formed in the product(s).
pH is a measure of the acidity in a solution and is determined using a logarithmic scale.
Each number on the pH scale represents a 10-fold change in pH.