all about atoms, elements and compounds

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all about atoms, elements and compounds
2015-12-01 08:14:51
chemistry revision (first chapter)
revise all of them very carefully! good luck:)
Show Answers:

  1. what are atoms?
    atoms are the smallest part of an element that can exist.
  2. what are elements?
    elements are made up of only one type of atom.
  3. what are compounds?
    compounds are substances that are made up of 2 or more elements, chemically joined together.
  4. how many atoms can there be in the first shell?
  5. how many atoms can there be in the second and third shell?
  6. is the atomic mass and mass number the same thing?
  7. what does the MASS number consist of?
    protons and neutrons.
  8. is there a difference between the proton number and the atomic number?
  9. what does the proton number consist of?
    no. of protons (also the no. of electrons).
  10. how do you find the number of neutrons when your given the mass number and the proton number?
    just subtract the mass number from the proton number.
  11. where in the periodic table is the proton number and the mass number situated?
    proton number is at the bottom and the mass number is at the very top.
  12. what is the key word for covalent and ionic?
    • Covalent - sharing
    • Ionic - transferring
  13. what are covalent bonds?
    A covalent bond is formed between non metal atoms, which combine together by sharing electrons. Covalent compounds have no free electrons and no ions so they don't conduct electricity.
  14. what are ionic bonds?
    it is when one electron of an atom is transferred to another element. so one loses its electron and one gains.
  15. what charge does an atom have when one of its electrons have been lost ?
    positive charge.
  16. what charge does an atom have when it has gained an electron?
    negative charge.
  17. how many elements occur naturally on earth?
    92 elements.
  18. state the trend in reactivity of the group 1 elements.
    the reactivity increases as you go down the group.
  19. why are potassium and sodium in the same group of the periodic table?
    • both have similar properties
    • both have one electron in their outer shell.
  20. explain why metals are good conductors of electricity?
    as the electrons are free to move in a network of atoms which makes them good conductors of electricity.
  21. what is the relative charge for proton, neutron and electrons?
    • proton: +1
    • electron: -1
    • neutron: 0