T1 : Atomic structure

• atom

  the smallest unit of matter

  
• element

  a substance made of only 1 type of atom
• molecule

  a substance made of two or more atoms joined together by a bond
• compound

  a substance made of at least two different types of atom chemically bonded together
• mixture

  two or more substances that are mixed together but are not joined by bonds
• nucleus

  the centre part of an atom that contains the protons and neutrons
• proton

  sub-atomic particle that makes up the nucleus of an atom, has a mass of 1 and a charge of +1
• neutron

  sub-atomic particle that makes up the nucleus of an atom, has a mass of 1 and a charge of 0
• electron

  sub-atomic particle found orbiting the nucleus in an electron shell, has a mass of almost 0 and a charge of -1
• ion

  an atom that has lost or gained electrons to become charged, lost electrons leave a positive ion, gained electrons leave a negative ion
• conservation of mass

  a rule that says you must have the same amount of atoms at the end of a chemical reaction as you started with
• electron shell

  one of the regions outside of the nucleus where electrons can be found
• filtration

  a technique used to separate an insoluble substance from a solvent (one that does not dissolve)

  
• crystallisation

  a technique used to separate a soluble solid (or salt) from a solution

  
• distillation

  a technique used to obtain the solvent (or liquid) from a solution

  
• fractional distillation

  a technique used to separate two miscible liquids (ones that do mix together)

  
• chromatography

  a technique commonly used to separate a mixture of dyes in ink

  
• J.J. Thomson


  the scientist who discovered the electron and proposed the plum pudding model
• plum pudding model

  a model of the atom that proposed the nucleus was a ball of positive charge with negative electrons embedded in it (we now know this is incorrect)

  
• Rutherford's experiment

  the experiment that proved the nucleus must be positively charged (as alpha particles were scattered/deflected by a piece of gold foil)

  
• Niels Bohr

  the scientist who proposed that electrons are found in shells
• James Chadwick


  the man who proposed the existence of neutrons
• isotope

  atoms of the same elements with the same atomic number but different mass numbers (different numbers of neutrons in the nucleus)
• Trends going down group 7

  Relative molar mass increases and boiling point increases
• Who was Dmitri Mendeleev?

  A Russian chemist and inventor
• What did Mendeleev's periodic table predict?

  New elements not yet discovered
• How are elements arranged in the periodic table?

  By increasing atomic number
• What does the atomic number represent?

  The number of protons in an atom
• What is found within each box of the periodic table?

  The nucleus symbol for that element
• What does the atomic number indicate?

  Number of protons in the atom
• What does the mass number represent?

  Total number of protons and neutrons
• What pattern did Mendeleev notice while organizing the table?

  Elements displayed repeating chemical properties
• What do elements in the same vertical column share?

  Similar chemical properties
• Why do elements in each group have similar properties?

  They have the same number of outer electrons
• How many electrons do Group 2 elements have in their outer shell?

  Two electrons
• What do all Group 1 elements have in common?

  One electron in their outer shell
• How do Group 1 elements react with water?

  They react violently
• What trend is observed in Group 1 elements as you move down the group?

  They become more reactive
• What do Group 7 elements have in their outer shell?

  Seven electrons
• How does reactivity change in Group 7 elements as you go down the group?

  They become less reactive