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Matter
- Refers to anything that has mass and occupies space
- Exists in three states: Solid, liquid and gas
- Composed of basic substances called elements
Element
Substance that cannot be broken down into other substances with different properties; composed of one type of atom
92 are naturally occurring
Carbon - Hydrogen - Nitrogen - Oxygen - Phosphorus - Sulfur
The 6 elements that make up 96% of the body weight of organisms
Atom
- Smallest part of an element that displays the property of the element
- Shares the same name as its element
- Composed of subatomic particles: protons, neutrons and electrons
Protons
Neutrons
Electrons
- Contained in the central nucleus of an atom, positively charged, 1 amu, contains mass
- Contained in the central nucleus of an atom, no charge, 1 amu, contains mass
- Contained in the orbiting clouds around nucleus (electron shells), negatively charged, very low mass - negligible in calculations
Atomic Number
- Equal to the number of protons in each atom of an element
- Atoms are assumed to be electrically neutral so typically the number of electrons = number of protons
Mass Number (Atomic Mass)
Equal to the sum of the number of protons and neutrons in atom's nucleus
Periodic Table (Dmitri Mendeleev)
- Atoms of an element are arranged horizontally by increasing atomic number in rows called periods
- Atoms of an element arranged in vertical columns are called groups and share the same binding characteristics
- Atoms shown here are electrically neutral
Groups (Periodic Table)
Atoms within the same column on the periodic table share the same chemical binding characteristics
Example: Group VIII are noble gases and are inert
Isotopes
Atoms of the same element that differ in the number of neutrons and thus have different atomic masses
Some spontaneously decay (Radioactive rays or subatomic particles) and can be helpful or harmful
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