Atomic structure

• What was order of people who made theories about the atom and when?

  • First - John dalton:
• What was order of people who made theories about the atom and when?

  Second - J.J Tomson (1897)
• John dalton's theory about the model of an atom

  Came first, Published 3 part atomic theory: 1)All substances are made up of atoms, atoms are small particles - can't be created, divided or destroyed. 2) Atoms of the same element are exactly alike, atoms of different elements are different. 3)Atoms join with other atoms with make new substances.
• JJ Tomsons theory about the model of an atom

  Plum pudding model: Negative electrons are scattered throughout soft blobs of positively charged material. Conducted an experiment with a cathode ray tube, Discovered atoms can be divided into smaller parts - beam moved away from negatively to positvely charged plate showing particles had a negative charge.
• What model did JJ tomson find?

  Plum pudding model
• What is the plum pudding model?

  Negative electrons are scattered throughout soft blobs of positively charged material.
• What did JJ Tomson conduct the experiment with?

  Cathode ray tube
• What did JJ Tomson discover proving Daltons original theory wrong?

  Atoms can be divided into smaller parts.
• What happened in JJ Tomson's experiment?

  The beam moved away from the negatively charged plate to the positively charged plate showing there's negative electrons scattered through blobs of positively charged material.
• What was the order of people who made theories about the atom and when?

  Third - Ernest Rutherford (1909)
• Ernest Rutherford's theory about the atom

  Shot a beam of positively charged particles into a sheet of gold foil. Most beams continued in a straight line (as expected from plum pudding model) but some particles deflected off the side and some bounced back. - Rutherford developed a new model saying most of the atoms mass is found in a region in the centre called the nucleus. In his model: Most of the atom is empty space and the electrons travel in random paths around the nucleus.
• What did Ernest Rutherford do in his experiment?

  Shot a beam of positively charged particles onto a gold foil sheet. Most of the particles when straight through (as expected from plum pudding model) but some deflected off the sides and some bounced back.
• What was Ernest Rutherford's theory?

  Most of the atom's mass is found in a region in the centre called the nucleus.
• What does Ernest Rutherford's model look like?

  Most of the atom is empty space and the electrons travel around the nucleus in random paths.
• The structure of an atom is a nucleus containing protons and neutrons, surrounded by electrons in shells.
• The relative charge of a proton is +1
• The relative mass of a proton is 1
• The relative mass of neutron is 1
• The relative charge of a neutron is 0
• The relative charge of an electron is -1
• The relative mass of an electron is 1/1836
• Why do atoms contain an equal number of neutrons and protons?

  Atoms​ ​are​ ​neutral​ ​and​ ​the​ ​charges​ ​on​ ​a​ ​proton​ ​are​ ​+1​ ​and​ ​on​ ​an​ ​electron​ ​are​ ​-1 therefore​ ​amount​ ​of​ ​protons​ ​=​ ​amount​ ​of​ ​electrons,​ ​so​ ​that​ ​the​ ​charges​ ​cancel
• The nucleus of an atom is very small compared to the overall size of the atom.
• Most of an atoms mass in concentrated in the nucleus
• Mass number

  Number of protons + number of neutrons
• Atoms of a given element always have the same number of protons in the nucleus and this number is unique to the element.
• Isotopes are different atoms of the same element containing the same number of protons but different number of neutrons in their nuclei.
• Atomic number

  Amount of protons
• Amount of protons and electrons are the same
• How does the existence in isotopes result in relative atomic masses of some elements not being whole numbers?

  Isoptopes have the same number of protons but different number of neutrons, they're still atoms of the same element, but have different atomic masses. The relative atomic mass is calculated using the abundance of different isotopes and its an average it can lead to the relative atomic mass not being a whole number. Since mass of atoms are small, we compare their masses to eachother.
• What is a metal

  Elements that react to form positive ions
• What is a non metal

  Elements that don't form positive ions
• What is a molecule?

  2 or more atoms that are chemically bonded togeather. E.g) oxygen, chlorine and water
• What is a compound?

  Two or more different elements held togeather by chemical bonds E.g) water, carbon dioxide.
• Compound elements are always found in the same proportion so we can write formulas
• What's a mixture?

  2 or more substances that are not chemically bonded, They haven't reacted and can easily be separated.
• Whats an ion

  Charged particle formed by the gaining or losing of an electron
• Why do atoms lose or gain electrons?

  To make a full outer shell
• Why don't groups 3,4,5 form ions easily?

  They need to lose or gain a larger number of electrons and therefore more energy is required.
• Metals are more reactive as you go down the table because there are more shells which are further from the nucleus, the protons in the nucleus can't hold onto the electrons more strongly so the atom loses the electrons faster therefore being more reactive.