C1 - Atomic Structure and The Periodic Table

• How are elements arranged in the Periodic Table?

  • Elements are arranged in order of ATOMIC (proton) NUMBER and so that elements with similar properties are in columns, known as GROUPS
  • Elements in the same PERIODIC GROUP have the same amount of ELECTRONS in their OUTER SHELL, which gives them similar CHEMICAL PROPERTIES
• Why was Mendeleev's Periodic Table widely accepted than previous versions?

  • Mendeleev had predicted properties of missing elements
  • Elements were discovered that filled these gaps
  • The properties of these elements matched Mendeleev’s predictions
• Where are Metals found in the Periodic Table?

  • Found to the left of the Periodic Table
• Where are Non-Metals found in the Periodic Table?

  • Found towards the right of the Periodic Table
• Metals LOSE electrons to form...

  • Positive Ion + Full Outer Shell
• Non-Metals GAIN electrons to form...

  • Negative Ion + Full Outer Shell
• Before the discovery of Protons, Neutrons and Electrons how did Scientists arrange elements?

  • Scientists arranged elements in order of their Atomic Weight
• State the properties of Alkali Metals

  • Single electron in their outer shell
  • Reacts vigorously with water to create -> Alkaline solution + Hydrogen
  • React with oxygen to create -> Oxide
  • They all react with chlorine to form -> White Precipitate
• What happens to the reactivity when going down Group 1 (Alkali Metals)

  • The reactivity of elements INCREASES
• Fill out the blanks describing the reactions of the first 3 Alkali Metals with Oxygen, Chlorine and Water:

  ALKALI METALS

  A) Red

  B) Burns

  C) Flame

  D) White Solid

  E) Orange Flame

  F) White Solid

  G) Large

  H) Lilac

  I) Flame

  J) Smaller

  K) Solid Immediately

  L) Fizzes Steadily

  M) Dissolves

  N) Fizzes Rapidly

  O) Melts

  P) Ball

  Q) Dissolves Quickly

  R) Ignites

  S) Sparks

  T) Lilac Flame

  U) Quickly

  V) Dissolves

  W) White Powder

  X) Settles

  Y) Sides

  Z) Container

  [) Burns

  \) Yellow

  ]) Flame

  ^) White

  _) Powder

  `) Settle

  a) Sides

  b) Container

  c) Vigorous

  
• State the properties of Noble Gases

  • 8 Electrons in their outer shell, except helium which has 2. All of them have full outer shells
  • Unreactive and do not easily form molecules, because they have a stable arrangement of electrons
• What happens to the boiling points when going down Group 0 (Noble Gases)

  • The Boiling Point of the Noble Gases increase with increasing relative atomic mass
• State the properties of The Halogens

  • Similar reactions due to their seven electrons in their outer shells
  • They are non-metals and exist as molecules made of pairs of atoms (Diatomic Molecules)
• What happens when The Halogens react with metals?

  • They react with metals to form ionic compounds in which the halide ion carries a -1 charge
• What happens when The Halogens react with non-metals?

  • They react with non-metals to form covalent compounds, where there is a shared pair of electrons
• What happens to the Melting Point, Boiling Points and Relative Molecular Mass when going down Group 7 (The Halogens)

  • The Melting / Boiling Point and Relative Molecular Mass increases
• What happens to the reactivity when going down Group 7 (The Halogens)

  • The reactivity of elements decreases because:
  • Halogens react by GAINING an electron (To obtain a full outer shell)
  • The number of SHELLS increase down the group, so down the group the element attracts electrons from other atoms less, so can't react easily
• What happens in the displacement of halogens in a aqueous solution of its salt?

  • The more reactive halogen can displace a less reactive one in an aqueous solution of its salt
  • E.g. Chlorine will displace Bromine if we bubble the gas through a solution of Potassium Bromide
• State the relative masses and relative charges of the Protons, Neutrons and Electrons

  • Protons -> Relative Mass: 1 / Charge: +1
  • Neutron -> Relative Mass: 1 / Change: 0
  • Electrons -> Relative Mass: 0 / Charge: -1
• Explain why atoms are electrically neutral

  • They have the same number of electrons and protons
• What is the radius of an atom?

  • 0.1 nm
• What is the radius of a nucleus?

  • $1\times10^{-14}$
• What is the Atomic Number?

  • The number of PROTONS in a nucleus
• Where is the majority of the mass of an atom?

  • The nucleus
• What is the mass number?

  • The total number of PROTONS and NEUTRONS
• What are isotopes?

  • An element which has the same number of PROTONS but, different number of NEUTRONS
• How do we calculate the number of NEUTRONS using the Mass Number and the Atomic Number?

  • Mass Number - Atomic Number
• What are Mixtures?

  • Mixtures are substances that are made up of elements and compounds that AREN'T chemically bonded
• What are Compounds?

  • Compounds are substances that are made up of two or more elements chemically bonded
• State the equation for Relative Atomic Mass (RAM)

  • $\frac{Isotope\ Abundance\ \times Isotope\ Mass\ Number}{100}$
• Atoms

  • Atoms make up all substances and are the smallest part of an element that can exist
• What did scientists think atoms were BEFORE the discovery of electrons?

  • Proposed by John Dalton -> An atom was though to be tiny spheres that could NOT be divided
• What was the Plum Pudding?

  • Proposed by J.J Thomson -> Suggested that an atom is a ball of positive charge with negative electrons embedded in it
• What was the Alpha-Scattering Experiment?

  • Performed by Rutherford -> Led to the conclusion that the mass of an atom was concentrated at the centre (nucleus) and that the nucleus was charged
• Explain the steps of the Alpha-Scattering Experiment, and what did this show?

  • A beam of alpha particles was fired at a very thin gold foil
  • Most of the alpha particles passed straight through the gold foil, without changing direction -> Atom is mainly empty space
  • Some of the alpha particles bounced straight back -> Centre of atom contains the most mass
  • The positively charged alpha particles were being repelled and deflected -> Small concentration of positive charge in the centre of the atom (nucleus)
• The results of the Alpha-Scattering Experiment led to...

  • The replacement of the Plum Pudding Model with the Nuclear Model
• Label the Nuclear Model

  Nuclear Model

  A) Negative Electrons

  B) Empty Space

  C) Positive Nucleus

  
• What changes did Neil Bohr make to the Nuclear Model?

  • He suggested that electrons orbit the nucleus at specific distances
• Who discovered the existence of neutrons?

  • James Chadwick
• Describe 3 differences between the Nuclear Model and the Plum Pudding Model

  • In the Nuclear Model, the atom is mostly empty space / Plum Pudding has no empty space
  • In the Nuclear Model, the positive charge is all in the nucleus / Plum Pudding is a ball of positive charge
  • In the Nuclear Model, the mass is concentrated in the nucleus / In the Plum Pudding the mass is spread out