SC17 Groups in The Periodic Table Flashcards
SC17
What groups are elements found in, in the periodic table:
1) Alkali metals
2) Halogens
3) Noble gases
1) Alkali metals are found in group 1
2) Halogens are found in group 7
3) Noble gases are found in group 8/ group 0
SC17a
1) What are the main physical properties of alkali metals (are they malleable, do they conduct electricity, are they soft metals, what kind of melting points do they have)?
2) Describe the reactions of lithium, sodium and potassium with water
1) The alkali metals are malleable, conduct electricity, soft metals that can be cut with a knife, and have relatively low melting points.
2) Lithium: bubbles fiercely on the surface
Sodium: Melts into a ball and fizzes on the surface
Potassium: The hydrogen gas bursts into flames and the potassium violently fizzes about the surface of the water
SC17a
1) Describe the pattern of reactivity of the alkali metals
2) Explain how the electronic configurations of the atoms of alkali metals affect their reactivity, and how they will react.
1) The reactivity of alkali metals increases down the group.
2) These atoms have one electron on their outer shells. As you go down group 1, the outer shell electron is further away from the nucleus, and therefore less attracted to it. This means that it is easier to remove the outer shell electron. If they are more reactive, then they will react more violently and may explode.
SC17b
What is the appearance of the following halogens at room temperature?
1) Bromine
2) Iodine
3) Chlorine
1) Bromine is a brown liquid
2) Iodine is a grey-black solid
3) Chlorine is a green gas
SC17b
1) What are the trends for colour going down the halogen group?
2) What are the trends for boiling point going down the halogen group?
3) What are the trends for state at room temperature going down the halogen group?
1) The halogens become darker as you go down the group.
2) The melting and boiling points increase as you go down the group.
3) There is a trend in state at room temperature from gas to liquid to solid as you go down the group.
SC17b
1) How do halogens react with hydrogen, and what does it form when dissolved in water?
2) How do halogens react with metals?
3) Describe the pattern of reactivity of the halogens?
4) Explain how the reactivity of halogens can be worked out from displacement reactions
1) Halogens react with hydrogen to form hydrogen halides, which dissolve in water to form an acidic solution.
2) Halogens react with metals to form ionic compounds called salts, which contain halide ions.
3) In halogens, reactivity decreases down the group.
4) In a displacement reaction, a more reactive halogen is added to a halide solution. The more reactive halogen pushes out and replaces the less reactive halogen.
SC17b
1) What is the test for chlorine gas?
2) What colour is universal indicator at pH0, neutral, and pH14?
1) Damp blue litmus paper is used. The litmus paper must be damp. If the blue litmus paper is bleached white, then the substance contains chlorine.
2) Universal indicator is red when the substance is very acidic (pH0), green when the substance is neutral (pH7), and purple when the substance is very alkaline (pH14).
SC17d
1) What does the term ‘inert’ mean?
2) Describe the electronic structure of noble gases.
3) What is helium and neon used for?
1) Inert means that something does not react easily with anything.
2) Noble gases have a full outer shell of electrons, giving it a stable surface electronic structure. It won’t easily give up or gain electrons, making it inert. This means that it will not react with anything.
3) Helium is used to fill balloons because of it has a lower density than air. Neon produces a red light when electricity is passed through it, so it is used for making illuminated signs.
SC17d
1) What do noble gases look like, what are their melting points, and do they conduct electricity and heat?
2) What is the pattern of reactivity of the noble gases, and how does the boiling point change as you go down the group?
1) Noble gases are colourless, have low melting and boiling points, and and they are poor conductors of heat and electricity.
2) As you go down group 0, the reactivity increases, and the boiling point of noble gases increases.
SC17c
1) Explain how displacement reactions are examples of redox reactions
2) Explain the order of reactivity of halogens (using electronic configurations)
1) Oxidation is the gain of oxygen, or loss of electrons, by a substance during a chemical reaction. Reduction is the loss of oxygen, or gain of electrons by a substance during a chemical reaction. Reduction and oxidation happen at the same time, so the reactions are called redox reactions. Displacement reactions are one example of this.
Use the acronym OIL RIG to remember which one is which: Oxidation Is Loss (of electrons), Reduction Is Gain (of electrons).
2) As we go down the halogen group: there are more electrons shells between the nucleus and the outer shell of electrons. This means that the force of attraction between the nucleus and outer electron decreases and it becomes harder to gain an outer electron. Therefore, the reactivity of halogens decreases down the group.
SC17c
1) How do you write the ionic equation for the reaction of aqueous chlorine and aqueous potassium iodide?
2) How do you write the balanced equation for the reaction of aqueous chlorine and aqueous potassium bromide?
Step 1: Write out the full balanced equation:
2KI (aq) + Cl2 (aq) → 2KCl (aq) + I2 (aq)
Step 2: Identify the ionic substances and write down the ions separately
2K+ (aq) + 2I- (aq) + Cl2 (aq) → 2K+ (aq) + 2Cl- (aq) + I2 (aq)
Step 3: Rewrite the equation eliminating the ions which appear on both sides of the equation (spectator ions ) which in this case are the K+ ions:
2I- (aq) + Cl2 (aq) → 2Cl- (aq) + I2 (aq)
2) e.g Chlorine + Potassium Bromide
Chlorine + Potassium Bromide → Potassium Chloride + Bromine
Cl2 (g) + 2KBr (s) → 2KCl (s) + Br2 (g)
