SCIENCE 3RD MID

• Matter - anything that occupies space and has mass.
• Matter - is composed of atoms and molecules.
• Atom - smallest unit of elements
• Molecules - smallest unit of substance
• Solid - forms from liquid to gas because the energy of atoms decreases when the atoms take up a relatively ordered, three dimensional structure.
• Liquid - type of matter with specific properties that make it less rigid than a solid but more rigid than a gas.
• Gas - substance that is gaseous or vaporous
• Gas - it has no fixed shape or volume
• Isotopes - two atoms with the SAME ATOMIC NUMBER but different numbers of neutrons
• Physical properties - characteristics that CAN BE OBSERVED without changing the substance into another substance.
• Atom - composed of different particles called protons, electrons.
• Molecule - it is made up of atoms bonded together
• Gas - A lot of spaces between particles
• Liquid - little spaces between particles
• Solid - no spaces between particles
• Pure substances - are forms of matter that have definite chemical composition
• Pure substances - it is classified as elements and compounds
• Elements - substances are the substances that are made up of only one type of atom.
• Elements - they exist as monoatomic, diatomic, & polyatomic.
• Monoatomic molecules - composed of only one atom
• Diatomic molecules - composed of two atoms of the same element
• Polyatomic molecules - composed of more than two atoms of the same element.
• Ernest Orlando Lawrence - He was an American nuclear scientist.
• Ernest Orlando Lawrence - A Nobel prize winner in physics for his invention of cyclotron.
• Cyclotron - a device used to discover many artificial radioactive elements.
• The number 103 element called lawrencium(Lr) was named in his honor after it's discovery in 1951 at berkely
• Radioactive elements - type of chemical element that has an unstable nucleus, which means it tends to change or break down into a more stable nucleus over time.
• Radioactive decay - a breakdown process where in an element emits radiation in the forms of particles or energy.
• Give an example of radioactive element.

  • Cobolt -60
• Cobolt -60 - it is an element used to treat cancer.
• compounds - substances that are made up of more than one type of atom.
• Mixtures - made up of two or more substances that are physically combined.
• Mixtures can be categorized by:

  1. Homogeneous mixtures
  2. Heterogeneous mixtures
• Homogeneous mixtures - has a uniform composition and the same properties throughout, such as salt, dissolves in water.
• Solution - type of homogeneous mixtures where one substances (called the solute) is uniformly dissolved in another substances (called the solvent) to form a single-phase mixture.
• Solutions are made up of two parts:

  1. Solute
  2. Solvent
• Solute - which gets dissolves
• Solvent - which does the dissolving
• Heterogeneous mixtures - substances that consist of two or more different materials or components that are visibly distinguishable and not uniformly distributed.
• Heterogeneous mixtures - their components maintain their individual