CHEMISTRY

• element


  substance that CANNOT be chemically broken down into simpler substances

  
• atom


  smallest part of an element that can be identified as that element

  
• nucleus


  center, or core, of an atom (where the protons and neutrons are located)

  
• proton


  particle that has a positive charge - located in the nucleus of an atom. You can figure out the number of protons by looking at the atomic number of an element.

  
• neutron


  particle that has no charge - located in the nucleus of an atom. You can figure out the number of neutrons by SUBTRACTING the atomic Mass minus the atomic number.

  
• electron


  particle that has a negative charge - located in rings outside the nucleus of an atom. You can figure out the number of electrons by looking at the atomic number of an element.

  
• atomic number


  number of protons in the nucleus of an atom. This is the same number as the number of electrons

  
• atomic mass


  total mass of the protons and neutrons in an atom

  
• energy level


  place in an electron cloud where an electron is most likely to be found - rings. Remember, 2-8-18-32.

  
• metal


  element that has the property of shiny luster, ductility, and malleability

  
• luster


  the way a material reflects light

  
• malleable


  able to be hammered into different shapes

  
• ductile


  able to be drawn into thin wires

  
• nonmetal


  element that lacks most of the properties of a metal, is not shiny, does not conduct electricity or heat well, is not malleable so it is called brittle or breakable.

  
• halogens


  elements that make up Group 17 in the periodic table

  
• noble gases


  elements that make up Group 18 in the periodic table

  
• matter


  anything that has mass and takes up space

  
• properties


  characteristics used to describe an object

  
• state of matter


  any of the four physical forms of matter

  
• solid


  state of matter with a definite shape and volume

  
• liquid


  state of matter with a definite volume but no definite shape

  
• gas


  state of matter that has no definite shape or volume

  
• plasma


  state of matter made up of electrically charged particles - needs high temperatures and high pressure

  
• chemical formula


  way of writing the name of a compound using chemical symbols

  
• subscript


  number written to the lower right of a chemical symbol in a chemical formula

  
• chemical equation


  statement in which chemical formulas are used to describe a chemical reaction

  
• coefficient


  number that shows how many molecules of a substance are involved in a chemical reaction

  
• chemical reaction


  process in which new substances with new chemical and physical properties are formed

  
• reactant


  substance that is changed in a chemical reaction

  
• product


  substance that is formed in a chemical reaction

  
• molecule


  smallest part of a substance that has all the properties of that substance - more than one element, like hydrogen and oxygen make water

  
• chemical bond


  force of attraction that holds atoms together

  
• freezing


  change from a liquid to a solid

  
• melting


  change from a solid to a liquid

  
• evaporation


  change from a liquid to a gas at the surface of the liquid

  
• condensation


  change from a gas to a liquid

  
• sublimation


  change from a solid directly to a gas

  
• physical change


  change that does not produce new substances - melting an ice cube or ripping paper. You can get the ice back and the paper is still paper.

  
• chemical change:


  change that produces new substances - burning wood to make ashes or mixing mentos and coke. You can't get the wood or the mentos back.