atomic structure & periodic table

• what are the charges and masses of protons, neutrons and electrons?

  Proton = mass 1 charge +1Electron = mass 0 charge -1neutron = mass 1 charge 0
• why do atoms have no overall charge?

  they have equal numbers of protons and electrons
• what is an element?

  made of only one type of atom
• what is a compound?

  a substance made of more than one element chemically bonded together
• what does the atomic number show?

  the number of protons in the nucleus
• what does the mass number show?

  the number of protons and neutrons in the nucleus
• what are isotopes?

  atoms of the same element with the same number of protons but different numbers of neutrons
• what is the relative atomic mass of an element?

  Average mass of an element's isotopes
• how can you calculate the RAM using mass numbers of its isotopes and % abundance?

  RAM = sum of (isotope abundance x isotope mass number) / sum of abundances of all the isotopes
• what is a mixture?

  substances made of compounds and/or elements that aren't chemically bonded together
• how can you seperate an insoluble solid from a solution?

  filtration
• how can you separate mixtures of liquids with similar boiling points?

  Fractional distillation
• how can you separate mixtures of liquids of different colors?

  chromatography
• in paper chromatography, why must the origin line be in pencil?

  as pencil is insoluble so it wont dissolve in the solvent
• why do you place a lid on top of the container in paper chromatography?

  to stop the solvent evaporating
• how do you carry out crystallization?

  -heat in an evaporating dish on bunsen burner until almost all liquid has evaporated

  -then leave solution to cool

  -filter the crystals out of solution and leave in warm place to dry
• in fractional distillation, where is the coolest part of the column?

  Top
• who describes atoms as solid spheres in the early 19th century?

  John Dalton
• who discovered the electron?

  J.J. Thomson
• what was jj thomsons atomic model called?

  Plum pudding model
• whose experiments provided evidence of the neutron?

  James Chadwick
• Rutherford and Marsden developed the nuclear model. They fired alpha particles at gold leaf. What did they show?

  most alpha particles went straight through. Some deflected and very few bounced back. This shows that there is a positive nucleus but most of the atom is empty space
• How did Niels Bohr develop the nuclear model?

  electrons are contained in shells
• how many electrons fit in the 1st, 2nd and 3rd energy shell?

  2,8,8
• what does the group number of an element tell you?

  the number of electrons in the outer shell
• what does the period number of an element tell you about the atom?

  the number of energy shells it has
• before Mendeleevs periodic table, how were elements arranged?

  in order of relative atomic mass
• how did Mendeleev overcome early problems with the periodic table?

  he left gaps
• what type of element forms positive ions when they react? where can they be found on the periodic table?

  Metals. They can be found on the left side of the periodic table.
• what kind of ions do non-metals form in ionic compounds?

  negative
• what are elements of group 1 called?

  Alkali metals
• state what trend in reactivity as you go down?

  reactivity increases down the group
• how many elements are in the periodic table?

  around 100
• what are the properties of metals?

  -strong

  -can be bent or hammered (malleable)

  -great at conducting heat and electricity

  -high boiling and melting points
• what are the properties of non-metals?

  -dull looking

  -brittle

  -dont usually conduct electricity

  -lower density
• how do alkali metals react with water?

  -fizz on surface

  -produce hydrogen gas

  -produce a metal hydroxide(alkaline)
• how do alkali metals react with chlorine?

  -vigorously

  -to produce a white metal chloride salt
• what si the equation showing how alkali metals react with water?

  Alkali metals + water -> metal hydroxide + hydrogen
• why is potassium more reactive than lithium?

  K is further down the group. Its outer electron is further from the positive nucleus and so is more shielded by electrons, making it easier to lose
• what happens to melting and boiling points as you go down group 1?

  they decrease