TSR Wiki > Study Help > Subjects and Revision > Revision Notes > Chemistry > Key Chemical Terms and Vocabulary
- Physical Change: a change that only affects the physical properties of an object
- Endothermic Change: a physical/ chemical change in which a system absorbs energy from its surroundings. (ex: melting and boiling)
- Exothermic Change: when energy is absorbed rather than given off. (ex: when a liquid becomes a solid or when raid forms and water freezes)
- Chemical Change: a change that produces one or more new substances.
- Chemical Properties:' properties that can be observed only when substances interact w/ each other.
- Extensive Properties: properties such as mass, volume, and length that depend upon the quantity of matter present.
- Intensive Properties: all chemical properties and some physical like melting and boiling point, color, density, texture etc which don’t depend up on the matter present.
- Metal: is solid at room temperature, grayish in color w/ a shiny surface and good conductor of heat and electricity. ( largest region of the periodic table)
- Non-Metal: anything that’s not a metalloid, metal or noble gas. They are poor conductors of heat and electricity.
- Noble Gases: non reactive w/ other elements and inert
- Law of Conservation of Mass: states that mass is neither created nor destroyed
- Law of Definite Composition: states a given compound contains exactly the same proportion of element by weight.
- Law of Multiple Proportions: states that when 2 elements form a series of compounds, the ratios of the masses of the 2nd element that combine w/ 1g of the first element can always be reduced to small whole numbers.
- Protons: positively charged
- Neutrons: not charged
- Electrons: negatively charged
- Cathode: negatively charged electrode through which current flows
- Anode: positively charged electrode through which type current flows
- Atomic Number: number of protons
- Isotopes: atoms w/ the same number of protons but different numbers of neutrons
- Mass Number: total number of protons and neutrons
- Compound: pure substance composed of 2 or more different element
- Elements: 109 simplest substances from which complex materials are made
- Mixtures: a collection of 2 or more pure substances physically mixed together
- Periodic Law: properties of elements tend to change w/ increasing atomic number in a period wave.
- Alkali Metal: reactive metallic elements which form alkaline solutions in water and burn in air. (group 1)
- Alkaline Earth Metals: reactive metallic elements that are harder, denser, and stronger and have higher melting points that the alkali. (group 2)
- Lanthanides: elements 58- 71 which are shiny, metallic and fill the 4f orbital.
- Actinides: metallic elements 90-103 that fill 5f orbital
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