From The Student Room

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

Comments