chap3 elements mixtures compounds

• elements are the basic building blocks of matter and cannot be separated in simpler substances
• mixtures contain two or more different substances which can be physically separated by physical means such as filtration, evaporation, distillation etc.
• compounds are made up from two or more elements that have been chemically combined together.
• mixtures are made up of two or more compounds and/or elements that are not chemically combined and can be separated by physical means
• Solubility refers to how well a solute dissolves in a fixed amount of time in a particular solvent.
• A solution is a homogeneous mixture where one substance (the solute) has completely dissolved into another substance (solvent).
• factors that affect the rate of dissolving

  -rate of stirring

  -temperature of solvent

  -surface area
• Filtration is used to separate insoluble solids from liquid-solid mixtures
• Paper chromatography is used to separate small amounts of mixtures based on different solubilities in the same solvent
• Evaporation is used to separate dissolved solids from liquid-solid mixtures
• Distillation is used to separate pure liquids from a liquid-liquid mixture or liquid solid mixture
• what apparatus do we use to measure mass?

  electronic balance or beam balance
• what apparatus is used for determining volume


  -measuring cylinders

  -beakers
• what apparatus do we use to determine length


  -digital calipers

  -rulers

  -measuring tape
• what are the properities of ceramic?


  -poor conductor of electricity

  -does not corrode(rust)

  -has a high melting point

  -fragile

  -can be moulded into shapes
• -what are the properties of glass?

  -high melting point

  -does not corrode

  -transparent

  -poor conductor of electricity

  -poor conductor of heat

  -can be moulded into different shapes
• what are properties of metal


  -shiny

  -good conductor of heat

  -good conductor of electricity

  -can be bent without breaking
• what are the properties of plastic


  -lightweight

  -does not corrode

  -has a low melting point

  -poor conductor of heat

  -poor conductor of electricity

  -can be moulded into shapes
• what are the further 2 levels of purification?


  -reverse osmosis

  • to remove disease causing microorganisms, dissolved salts and chemical molecules
  • microfiltration
  • to remove tiny particles from water
• characteristics of a image in a plane mirror

  -object size=image size

  -object distance from mirror=image distance from mirror

  -attitude (orientation) is always facing upright

  -always forms a virtual image

  -image is reversed- left to right
• characteristics of regular reflection?

  -occurs when parallel rays of light hit a smooth surface

  etc. plane mirrors- reflected as parallel rays
• state the characteristics of diffuse reflection

  -occurs when parallel rays of light hit a rough surface

  etc. frosted paper/rough paper

  -reflected off the surface at different angles

  -rough paper has many different angles of incidence

  -image is distorted
• what are convex mirrors?

  -shows a upright image that are always smaller than the object

  -has a large 'field of view' to see many things
• what are concave mirrors?

  -shows a upright magnified image if the objects are close to the mirror
• state the definition of refraction

  refraction is the bending of light as it passes through one transparent material to another of different optical density
• state a characteristic of refraction

  -speed changes as it travels through one transparent material to another. Light travels slower in materials that are optically denser
• parts of a cell in a animal

  -vacuole

  -cytoplasm

  -cell wall

  -nucleus

  -cell membrane
• parts of a cell in plants

  -cell wall

  -vacuole

  -nucleus

  -cytoplasm

  -chloroplast

  -cell membrane
• characteristics of a vacuole in animal cells

  -small and numerous

  -stores liquids,foods and waste materials
• characteristics of cytoplasm

  -site where most chemical reactions occur in the cell

  -jelly like substance
• characteristics of nucleus

  -contains dna- hereditary or genetic material that get passed down from parents to offspring

  -controls all activities that take place in the cell
• characteristics of cell membrane

  -thin outer layer that surrounds the cell

  -controls the movement of substances into and out of the cell

  -layer beneath the cell wall in the plant cell
• characteristics of chloroplast

  -allows plants to photosynthesise and make food

  -'food factory' of the cell
• characteristics of a cell wall in a plant cell

  -rigid and gives the cell a regular shape

  -protects and supports the cell

  -tough outer covering surrounding the cell membrane

  -allows substances to move in and out of the cell
• difference between the vacuole in a plant cell and a animal cell

  the vacuole in the plant cell is large and few while the vacuole in the animal cell is small and numerous
• pure substances melt at a fixed temperature
• difference between solution and suspension in terms of visibility

  there are no insoluble particles present in a solution and no insoluble particles can be seen while insoluble particles can be seen in a suspension.
• state the definition of refraction

  refraction is the bending of light at the boundary between 2 different transparent materials
• state the definition of reflection


  reflection is the bouncing of light off a surface
• state the characteristics of solid particles

  -particles are close together

  -particles are arranged in a fixed, regular position

  -particles cannot move freely, but vibrate constantly in their fixed positions