Term
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Definition
A man who tried to organise elements in 1864. He noticed that every 8th element (atomic mass order) had similar properties. These sets of 8 were called Newlands' Octaves however his pattern didn't work after the 3rd row. His work was criticised because:
1.His groups contained elements that didn't have similar properties
2.He mixed up metals and non-metals
3.He didn't leave any gaps for un-discovered elements |
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Term
| Who was Dmitri Mendeleev? |
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Definition
A man who tried to organise the elements - 1869. He put the elements in order of atomic mass but he left gaps in order to keep elements with similar properties in the same column.The gaps predicted the properties of un-discovered elements. His work was accepted because:
1.Elements in the same column had similar properties
2.He left gaps for the un-discovered elements
3.When the elements were found they fit in the pattern
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Term
| Describe the Modern Periodic Table. |
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Definition
1. The elements are arranged by their electronic structure
2.Apart from the transition metals, elements in the same group have the same number of electrons in their outer shells
3. The group number is equal to the number of electrons in their outer shell.
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Term
| Why do Group 1 metals get more reactive as you go down the group? |
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Definition
| The positive charge of the nucleus attracts electrons and holds them in place. The further from the nucleus the electron is, the less the attraction. The attraction of the nucleus is even less when there are a lot of inner electrons. This effect is known as shielding. The combination of increased shielding and distance means that an electron in a higher energy level is more easily lost. |
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Term
Why do Group 7 metals get less reactive as you go down the group? |
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Definition
| Increased distance and shielding also means that a higher energy level is less likely to gain an electron - there's less attraction from the nucleus pulling electrons into the atom. |
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Term
| What are the trends of Group 1 (The Alkali Metals)? |
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Definition
As you go down the metals.....
1.....become more reactive
....because the outer electron is more easily lost
....because of distance (it is further away from nucleus)
2.....have lower melting and boiling points
3....they have low density |
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Term
| What are the first 3 Group 1 Elements? |
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Definition
Lithium (Li)
Sodium (Na)
Potassium (K) |
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Term
| Why do The Alkali Metals form Ionic Compounds with Non- metals? |
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Definition
| They need to lose their one outer electron to form a 1+ ion so they always form ionic bonds - they produce white compounds that dissolve in water to form colourless solutions. |
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Term
| What happens when Lithium (Li), Sodium (Na) and Potassium (K) react with water? |
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Definition
Li reacts vigorously with water H20 (likewise Na, K). They fizz furiously and produce Hydrogen (H2). K gets hot enough to ignite it. A lighted splint will indicate H2 by producing a pop. They form Hydroxides that dissolve in water to give alkaline solutions.
2Li(s) + 2H20 ➙ 2LiOH(aq) + H2(g)
2Na(s) + 2H20 ➙ 2NaOH(aq) + H2(g)
2K(s) + 2H20 ➙ 2KOH(aq) + H2(g) |
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Term
What are the trends of Group 7 (The Halogens)?
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Definition
As you go down the halogens.....
1.....become less reactive
....because it's harder to gain an electron
....because of distance (it is further away from nucleus)
2.....have a higher melting point
3....they have a higher boiling point
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Term
| What are the first 3 Group 7 Elements? |
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Definition
Flurine (F)
Chlorine (Cl)
Bromine (Br)
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Term
Why do The Halogens form Ionic Compounds with Metals?
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Definition
| The halogens form 1- ions called halides (F-, Cl-, Br-) when they bond with metals. For example Na+Cl-. |
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Term
| Why will more reactive halogens displace less reactive ones? |
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Definition
A more reactive halogen can displace (kick out) a less reactive halogen from an aqueous solution of it's salt. For example Chlorine (Cl) can displace Iodine (I) from an aqueous solution of its salt (Potassium Iodide KI)
Cl2(g) + 2KI(aq) ➙ I2 + 2KCl(aq) |
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Term
| What are the trends of The Transition Elements? |
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Definition
1. They are good conductors of heat and electricity
2. They are very dense, strong and shiny
3.They are much less reactive than group 1 metals
4.They don't react as vigorously with water or oxygen
5.They're much denser, stronger & harder than group 1 |
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Term
| Name some Transition Metal (Compounds) which are good catalysts. |
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Definition
Iron - used in the Haber process for making ammonia
Maganese(IV)Oxide - used in the decomposition of hydrogen peroxide
Nickel - used to turn oil into fat for magarine |
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Term
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Definition
| Water containing dissolved Calcium ions (Ca2+) or Magnesium ions (Mg2+) which are present due to a reaction between acidic rain and Calcium (Ca) or Magnesium (Mg) compounds in rocks. |
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Term
| Where does Hard Water come from? |
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Definition
1. Carbon Dioxide (CO2) dissolves in rain water making it slightly acidic
2. Rainwater falls into rivers and streams which flow over rocks containing Calicium (Ca)
3. Ca compounds (eg. CaCO3) react with the solution
4. This makes Calcium Hydrogen Carbonate (Ca(HCO3)2 ) which is soluble in water, so releases Ca2+ ions
5. This water flows into reservoirs and into our domestic water supply |
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Term
| What happens when you use soap with Hard Water? |
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Definition
| It makes scum and scale and the soap doesn't lather. |
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Term
What happens when you heat Hard Water? |
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Definition
| When heated, hard water forms scale (Calcium carbonate) on the insides of pipes, boilers and kettles which reduce the efficiency of the heating system. This may need to be replaced - which all costs money. |
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Term
| Name some advantages of Hard Water. |
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Definition
1. Ca2+ ions are good for healthy teeth and bones
2.Studies have found that people who live in hard water areas are at a less risk of developing heart disease than people who live in soft water areas. |
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Term
| What is Temporary Hard Water? |
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Definition
Temporary hardness can be removed by boiling. When heated the Calcium Hydrocarbonate decomposes to form Calcium Carbonate which is insoluble.
Calcium Hydrocarbonate ➙ Calcium Carbonate + Water + Carbon Dioxide
Ca(HCO3)2(aq) ➙ CaCO3(s) + H2O(l) + CO2(g) |
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Term
| What is Permanent Hard Water? |
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Definition
| Permanent hardness cannot be removed by boiling. |
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Term
| How can hardness be removed in both types of Hard Water? |
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Definition
| Both types of hardness can be softened by adding washing soda (Sodium Carbonate - Na2CO3). The added Carbonate ions react with the Ca2+ and Mg2+ ions to make an insoluble precipitate of Calcium Carbonate and Magnesium Carbonate. |
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Term
| How can you use Titration to compare the hardness of water samples? |
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Definition
1. Fill a burette with 50cm3 of soap solution
2. Add 50cm3 of sample a into a flask
3. Use the burette to add 1cm3 of soap solution into flask
4.Put a bung in the flask and shake for 10 seconds
5. Repeat steps 3 & 4 until a long lasting lather is formed
6. Record how much soap was needed to create a long lasting lather
7. Repeat steps 1-6 with sample b |
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