biology

• What are the primary constituents of matter?

  Elements
• What distinguishes compounds from mixtures?


  Compounds are chemically bonded in a fixed ratio, while mixtures are not.
• What is the smallest part of an element?


  An atom
• How do compounds differ from the elements that make them up?


  Compounds have different chemical properties than the elements that compose them.
• What is a characteristic of mixtures?

  Mixtures do not have a fixed ratio.
• What happens to the properties of elements in a mixture?


  Mixtures retain the original properties of the elements they are made up of.
• What is a heterogenous mixture?


  A mixture where the components are in different phases and the composition is not uniform.
• Give an example of a heterogenous mixture.


  Chicken in soup
• What is a homogenous mixture?


  A mixture where the components are in the same phase and the composition is uniform.
• Give an example of a homogenous mixture.


  Air
• Why can mixtures be separated by physical methods?


  Because they are not chemically bonded together.
• What is filtration used for?


  To separate an insoluble solid from a liquid.
• How is filtration typically performed?


  By pouring the mixture into a funnel with filter paper into a beaker.
• What is solvation?


  It is the interaction of a solute with a solvent.
• What is recrystallisation used for?


  To purify a substance.
• Describe the process of recrystallisation.


  Filter out excess solute, heat to evaporate solvent, and add heated solvent to purify.
• What is evaporation?


  It is when the solution is heated so that the solvent evaporates and only the solute remains.
• What is distillation used for?


  To separate a solvent from a mixture.
• How does distillation work?


  By heating the solution to evaporate the solvent, which then condenses back to liquid.
• What is paper chromatography used for?


  To separate the coloured substances in a mixture.
• How does paper chromatography work?


  Components of the mixture separate as they move at different rates in the solvent.
• What does the kinetic molecular theory explain?


  It explains the physical properties of matter and changes of state.
• What does temperature in Kelvin measure?


  The average kinetic energy of particles.
• What is the standard unit of temperature in chemistry?

  Kelvin
• How does Kelvin relate to Celsius?


  Kelvin goes up in the same increments as Celsius.
• Convert 37ºC to Kelvin.


  310K
• What is the mass number of an atom?


  It is the sum of protons and neutrons.
• What is the atomic number of an atom?


  It is the number of protons or electrons.
• What are isotopes?


  Atoms of the same element with different numbers of neutrons.
• Why do isotopes have the same chemical properties?


  Because they have the same number of electrons and protons.
• How can isotopes differ physically?


  They can have different melting and boiling points due to different densities and masses.
• What does relative atomic mass (RAM) depend on?


  It depends on the number of nucleons in the nucleus.
• How is RAM defined?


  All RAM is relative to 1/12 of a carbon-12 atom.
• What are mass spectra used for?


  To determine the relative atomic masses of elements from their isotopic composition.
• How is RAM deduced using a mass spectrometer?


  By injecting a vaporised sample of an element into the mass spectrometer.
• What happens to atoms in a mass spectrometer?


  They are bombarded with electrons, making them positively charged ions.
• What do mass spectrometers detect?


  They detect ions, not neutral atoms.
• What are diatomic elements?


  Elements that are more stable when they are in pairs.
• How do diatomic elements behave in a mass spectrometer?


  They form diatomic molecules before becoming monoatomic.
• How can the abundance of diatomic elements be calculated?


  By using the abundance of monatomic atoms if the abundance of diatomic molecules is not given.