idk

?

Atomic structure

      24– Mass number (Protons + Neutrons)
Mg
      12– Atomic number (Protons + Electrons)

                                         Relative mass                                     Charge

Proton                                     1                                                       +1

Neutron                                   1                                                        0

Electron                            Very small                                               -1

Atoms are neutral because they have equal number of Protons and electrons so cancel each ther out.

Isotopes
It is an copy of an atom,same number of Protons/electrons but not neutrons.

12 13
C C                   Reaction same because same number of electrons. Carbon 13
6 6                    Will be heavier because it has more neutrons which control mass.
P=6 P=6
E=6 E=6
N=6 N=7

1 of 27

Group 1- Alkali metals

1 electron in outer shell

Called alkali metals because very reactive

React rapidly with oxygen, chlorine and water

As you go down it gets more reactive because......

 Outer electron is further from nucleus so less attraction and easier to lose.

2 of 27

Group 0- Noble gases

Full electrons in outer shell

Stable because electrons don’t need to be gained or lost

Very unreactive as full electrons in outer shell

As you go down..

 Boiling point increases as relative atomic masses increase

 Intermolecular force increases because atoms get bigger which is why force hard to separate

Very unreactive because no electrons moving as full outer shell so no reactions take place

3 of 27

Group 7- Halogens

7 electrons in outer shell

From molecules when when two atoms join by covelent bonds

From covenant compounds when they react with other non-metal atoms

As you go down it gets less reactive because..

Outer shell further from nucleus so less attraction and electron harder to gain

Melting and boiling points increase

Molecules get bigger

4 of 27

Ionic bonding

- When metal and non-metal transfer electrons to become ions

Properties of ionic bonding:

- Giant ionic latitice

- High melting and boiling points so ionic bonds are very strong and lots of energy needed to break them

- Solid ionic compounds don't conduct electricity because no free ions

- Dissolved or melted ionic compounds conduct electricity because ions free to move

5 of 27

Metallic bonding

- Positive ions, surrounded by delocalised electrons

- Electrostatic attrcation is attraction between positive object and negative object

- Strong electrostatic attraction between sea of delocalised electrons and positive metal ions

Properties of  metallic bonding:

- Giant metallic lattice

- High melting and boiling points so metallic bonds are strong and lots of energy needed to break bonds

- Conducts electricity and heat beacsue free ions. Also electrons carry thermal energy to let metals conduct heat

- Mallebale is shaping ions. When force is applied ions move - Ductile is drawn into wires. When you stretch it, it forms a wire. - In metals layers of atoms are able to slide over each other

6 of 27

Covalent bonding

- Takes place between non-metal elements

- Shaired pair of electrons

- Electroststic attrcation makes covelent bonds very strong

Substances containg covelant bonds have simple molecualr structures:

-The atoms in molecules are held by covelent bonds

-Low melting and boiling points, so gases and liquids

- Don't conduct electricity as no free ions

- Weak intermolecular force between molecules so don't need alot of energy to break

7 of 27

Giant covalent structures

- Always solid at room temperature because they have millions of covelent bonds so high melting and boiling point

Diamond

- Formed from carbon, makes four covelent bonds

- Has loads of covelent bonds which have to be broken when diamond is melted which requires loads of energy. Cannot conduct electricty as no free electrons

Silicon dioxide

-High metling and boiling point because loads of covelent bonds that requires lots of energy to be broken

Graphite                                                                                                                                              Makes 3 covelent bonds. HIgh melting and boiling point as many covelent bonds so lots of energy needed to break bonds. Soft and slippery as no covelent bonds between layers so can slide. Conducts heat and electricity because delocalised electrons that can move.

8 of 27

Graphene and fullerenes

Graphene

-Single layer of graphite,one atom thick. Very strong. Conductor of electricity because delocalised electrons can move. Used in electronics

Fullerenes

-Molecules of carbon atoms with hollow shapes. Hexagonal rings,five or six carbon atoms. Used to deliver drugs into body, for lubricants like machines stopping parts grinding together and catalysts which is to speed up reactiona

Carbon nanotubes

Shaped into long cylinders, rings form 6 carbon atoms, high tesile strength (stretched without breaking) Conductors of heat and electricity 

9 of 27

Polymers

- They are plastic

- Solid at room temperature because intermoleculer forces of attrcation are strong so lots of energy needed to break these forces so high melting point.

10 of 27

Conservation of mass

- No atoms are lost or made during chemical reactions so mass of products = mass of the reactants

24g of magnesium racted with 71g of chloride.Calculate mass of magnesium choloride.

Magnesium + chloride ----------> Magnesium cholride

24g             +    71g  ------------>  95g

11 of 27

The mole

602 000000000000000000000 = 6.02 times 10 to power of 23

      Number of moles =      Mass in g                                                                                                                                       -------------------------                                                                                                                    Mr (Relative formula mass)

You are given a smaple of calcuim carbonate (CaCO3) with a mass of 300g. Calculate number of moles of calcium carbonate in sugar.

 CaCo3          40+12+48=100                    300                                                                                                                                                 ---------    = 3 moles                                                                                                               100 

12 of 27

Concentration

Concentration (mol/dm3)=   Number of moles                                                                                                                                  -----------------------                                                                                                                         Volume (dm3)

If volume in cm-3 divide by 1000.

A solution has a concentration of 0.5 mol/dm3. Calculate the number of moles in 0.2dm3.

0.5 times 0.2 = 0.1 moles

13 of 27

Limiting reagents and excess

Home many moles of zinc iodine would be produced if we used 0.5 moles of zinc and 1 mole of iodine?

Zinc      + Iodine-----------> Zinz iodine

1 mole + 1 mole-----------> 1 mole

0.5      + 1 mole------------> 0.5 moles

Limiting + Excess

14 of 27

Redox

Oxidation and reduction 

Oxidation 

-Gain of oxygen

-Loss of electrons 

Reduction

-Loss of oxygen

-Gain of electrons

15 of 27

Reactions of metals

Metals and Oxygen

When a metal recats with oxygen, it forms metal oxide

Magnesium + oxygen ------------> Magnesium oxide

Metals ands acids

All acids contain hydrogen.   Hydrochloric ----> HCl  Sulfuric ---->H SO     Nitric---->HNO          When acids react with metals they form salt and hydrogen gas.

Acid + metal --------> Salt + Hydrogen                                                                                           Hydrochloric acid + magnesium -----> magnesium chloride  + Hydrogen

Magnesium is more reactive than hydrogen so magnesium can easily displace hydrogen from acids.

Metals and water

When metals react with water a metal hydroxide and hydrogen has formed.

16 of 27

Metals

Unreactive metals

Very unreactive metals are found in ground E.g gold,silver,platinum

Ores

Metals found in ores have reacted with other elements. Oxygen and other impurities(sand). Ores are rocks containing enough metal to make it cost effective to extract.

Smelting iron

1) Iron is placed in a blast furnace. Limestone and carbon is added.

2) Carbon displaces iron to form iron and carbon dioxide. Carbon takes care of oxygen +limestone takes care of impurities.

You can use carbon to extract any metal less reactive than carbon. Iron oxide is heated with carbon. Carbon is more reactive than iron so displaces the metal.

Smelting copper, same extraction as iron

17 of 27

Phytomining + bio-leaching

Phytomining

1) Plants absorb copper, making copper

2) Burn plants and get copper from ash

3)Use electricity (electrolysis) to get metal

Bioleaching

1) Microorganisms absorb copper

2) Use electricity (electrolysis) to get metal

18 of 27

Iron vs Steel

-Both made from iron

Iron

When iron is extracted it is almost pure. Pure iron is soft because atoms are in layers and can slide over each other. Pure iron is brittle (breaks easily) because impurities such as carbon.

Steel

Alloy of iron combined with carbon. Low carbon steel has small amount of carbon and can be shaped easily. High carbon steel harder than low carbon steel. Lots of carbon atoms distort layers and prevent them from sliding.

More reactive metals

Electrolysis is used for more reactive metals. Using electricity is very expensive. Aluminium is extracted with electrolysis because carbon can't displace it as aluminum is more reactive then carbon.

19 of 27

Acids,Alkalis and bases

Acids produce hydrogen ions ( H ) in aqeus solutions. ( Dissolve in water).

HCl (aq) ------>H  (aq) + Cl (aq)

Bases are chemicals which can neutralise acids and produce salt and water. Some bases are solid, if solid dissolves in water it is an alkali.

acid + base ----------> salt +water     H  (aq)  + OH   (aq) -------> H O

Aqueus solutions of alkalis contain hydroxide ions OH 

NaOH (aq) ---------> Na(aq) + OH (aq)

How to know if something is acid or alkali?

-PH probe, determines PH electronically. Tells you number of PH.

-Universal indicator, changes colour whether it is acid or alkali. Red shows acid. Blue shows Alkali.Green shows neutral.

-Litmus paper, red litmus paper only works with alkali and blue with acid.

20 of 27

Strong and weak acids

Strong acids fullt ionise in aqueous solutions Positive and negative part seperates completely.

HCl ------>H  + Cl   -Hydrochloric acid(stomach acid) -Sulferic acid -Nitric acid

Weak acids partially ionise in aqeuous solutions. H CO (aq) Reverse H (aq) + HCO  -Citric acid(lemons) -Ethanic acid (Vinegar) -Phosperic acid (fizzy drinks) -Carbonic acid

The PH scale

A high concentration of H ions (acids) will have low PH.

A low concentration of H  ions (basic) will have high PH.

As the PH scale decreases by 1 unit, concentration of hydrogen ions increases by 10 times.

21 of 27

Making salts

Salts produced are sometimes soluble and insoluble.

If you have 2 types of alkali liquids and don't know if it is a metal or metal carbonate. Put acid in and if it bubbles you know gas is produced which is what metal carbonate produces.

5 ways to make salts

1. Neutralisation: Acid + metal hydroxide      Alkali are soluble bases.                                                 Acid + Alkali ------------> Salt + water

2.Neutralisation: Acid + Metal oxide              Bases are insoluble                                                        Acid + base --------------> Salt + water

3.Neutralistaion: Acid + Metal carbonate        Metal carbonates are insoluble.                                   Acid + base -------------> Salt + water + carbon dioxide

4.Acid + Metal ----------> Salt + hydrogen ( Dangerous to use this)

5. Ammonia NH .Acts as a base  Can react with acids to make ammonium,salts which are used as fertiliser.

22 of 27

Rection

1) Reaction of acids with metals

Magnesium + hydrochloric acid -------> Magnesium chloride + hydrogen                                                 Mg          +  2HCl                 ---------> MgCl                        +  H

2) Reaction of acids with metal hydroxides

Sodium hydroxide  + Nitric acid ----------->Sodium nitrate + Water                                                            NaOH               + HNO        -----------> NaNO               + H O

3)Reaction of acids with metal oxides            

Calcium oxide + Nitric acid ---------------> Calcium nitrate + Water                                                             CaO           + 2HNO       ---------------> Ca (NO )           + H O

4) Reaction of acids with metal carbonates

Sodium carbonate+ Nitric acid---------------> Sodium nitrate+water + carbon dioxide                                      Na CO       + 2HNO      --------------> 2NaNO            + H O  + CO

23 of 27

Electrolysis

Splitting of ionic compounds using electricity. ionic compounds contain metals combined with non-metals.E.g Sodium (metal) Chloride(non-metal) (NaCl)     

Ionic compounds are made up of positive + negative ions. As solid ionic compounds cannot conduct electricity because ions cannot move around. But when ionic compounds are melted, the ions are free to move and conduct electricity. These liquids are called electrolysis.

Negative ions are attracted to positive elctrode ( Anode).

Positive ionss are attracted to negative electrode (Cathode)

24 of 27

Electrolysis of copper chloride

Chloride is attracted to the positive electrode because chloride is negative. At the positive electrode chloride loses electrons and turn into chlorine gas. Sodium does not form solids because it's more reactive than hydrogen, instead hydrogen gas is made.

25 of 27

Exothermic and endothermic

Exothermic reactions transfer energy to the surroundings. Often a temperature change. E.g When bonfire burns, it transfers heat energy to the surroundings.Objects near bonfire become warmer. 

Examples:

-Burning fuels

-Neutralistaion- If beaker is warm

- Resperation- Cells (Releases heat due to our body temp)

Endothermic take in energy from the surroundings. Energy usually transferred as heat energy, causing the reaction mixture and it's suroundings to get colder.

26 of 27

Reversible reactions

Normal reaction 

27 of 27

Comments

No comments have yet been made

Similar Biblical Hebrew resources:

See all Biblical Hebrew resources »See all fdf resources »