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You are going to find out what happens when you mix a solution of a halogen to a solution of a compound with another halogen . Predict the results using the table and filling in the empty table
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What do your results prove about the reactivity of the halogens - use the word displace or displacement in your answer
More reactive halogens will displace less reactive halogens and the reactivity decreases as we go down the group
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Write the word and chemical equations for the reactions which occurred
- Chlorine + potassium -> potassium + bromide
- bromide Chloride
- Cl2 + 2KBr ---> 2KCl + Br2
- Cl2 + 2Br- ----> 2Cl- + Br2
- Cl2 + 2KI -----> 2KCl + I2
- Cl2 + 2I- ------> 2Cl- + I2
- Br2 + 2KI -----> 2KBr + I2
- Br2 + 2I- ------> 2Br- + I2
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Trends in group 7
Melting and boiling points increase as you go down the group . Reactivity decreases as you go down the group
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The elements in group 0 are called the
Noble gases
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The elements in group 0 are
- Helium
- neon
- argon
- krypton
- xenon
- radon
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All the noble gases are
- Non metals and have very low melting and boiling points , hence they are all gases at room temperature . They are all chemically unreactive
- and so do not form compounds with any other elements and exist simply as individual atoms I.e He , Ne , Ar , Kr , Xe and Rn (rather than as molecules where 2 atoms join as with all other gases eg H2 , O2 , Cl2) . They are unreactive and monatomic because their outer electron shell is already full so the atoms have no tendency to gain , loose or share electrons
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uses of noble gases
They are used as inert (unreactive) gases in filament lamps and electrical discharge tubes
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In the periodic table between groups 2 and 3 is a block of elements known as the
Transition elements . These are all metals
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The transition elements have similar a properties and some special properties because
A lower energy level (inner shell) is Being filled in the atoms of the elements between groups 2 and 3 , this is because the third energy level Can hold up to 18 electrons , once two electrons have occupied the fourth energy level
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Compared with group 1 , transition elements
- Have higher melting point (except mercury) and higher densities
- are stronger
- are much less reactive and So don't react as vigorously with water or oxygen
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Many transition elements have ions with
Different charges , for example iron atoms can react to give away 2 electrons to form Fe2+ ions or give away 3 electrons Fe3+ ions . We use Roman numerals to show which charge the iron ions have in a compound e.g. There are two forms of iron oxide iron 11 oxide (formula FeO) and iron 111 oxide (formula Fe2O3)
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Nb if you aren't told in the name you can always assume all transition elements except silver Are
+2 , silver is always +1
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Unlike group 1 metals (which form white ionic compounds that dissolve to form colourless solutions) , transition metals form
coloured ionic compounds that often dissolve in water to form coloured solutions e.g. Copper 11 sulphate dissolves to form a bright blue solution . Iron 11 compounds are usually green coloured and iron 111 compounds are usually brown coloured . (E.g. Iron 111 oxide is brown)
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Transition metals are useful as
- Catalysts (substances that speed up a reaction without being used up themselves)
- Examples from the previous topic include iron in the haber process to make ammonia , nickel in the hydrogenation of vegetable oils to make margerine
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The vertical columns are called
Groups . They are numbered 1 to 0
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The horizontal rows are called
Periods there are 7 of these
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elements of the same group have the same sort of properties . What are the names of group 1 , group 7 and group 8
alkali metals , halogens , noble gases
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As you go down a group the number of electrons
Increases . Therefor the size of the atoms increases . But in any one group the number of electrons in the outer shell is always the same
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In group 1 there is .. Electron(s) in the outer shell
1
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In group 7 there are .. Electron(s) in the outer shell
7
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In group 8 there are .. Electron(s) in the outer shell
8
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If you didn't have a periodic table explain 3 ways in which you could decide if it was a metal or a nonmetal
- Metals would conduct electricity unlike nonmetals
- metals would conduct heat unlike nonmetals
- Metals would be sonorous unlike nonmetals
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Describe an experiment you could do to prove whether an element was a metal or nonmetal
Use the element in a circuit and see if the bulb lights up , if it does it means the element conducts electricity and therefor is a metal . However there is an exception because graphite is a nonmetal but still conducts electricity
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Why is the radius of a Cl- radius larger tthe the radius of a Cl atom
A Cl- ion has more electrons , electrons repel each other , so a larger radius
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What is the trend In melting and boiling points as you go down group 7
they increase
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The halogens exist as diatomic molecules . What does this mean
- 2 atoms in the molecule
- noble gases are monatomic they exist their own
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Why do halides form ions
They need to gain an electron so they have a Full outer energy level
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what type of bonding does chlorine form with nonmetals
Covalent
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What is a test for chlorine
See if it bleaches damp litmus if it does Cl is present
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Basic why does the reactivity decrease as you descend group 7
- Larger atoms
- outer electrons are more shielded
- so attraction from nucleus is less so electrons are gained less easily
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What happens to the atomic mass of the elements as we descend group 1
Increases
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Why
Because as we descend down the group the number of protons and neutrons increases
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As we descend down group 1 what happens to the size of the atoms and ions
Increase
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Why
More full energy levels
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Why is the radius of a sodium ions less than the radius of a sodium atom
The sodium ion has 1 less electron
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What have all the alkali metals have in common
They all have 1 electron in their outer energy level
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Why does this make them all reactive metals
Its easy to remove 1 electron
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On descending group 1 what happens to the melting and boiling points of the elements
They decrease
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The horizontal rows of the periodic table are know as periods . As we move across the period of a table
Each successive element has one more electron in its outer energy level than the element before it . This carries on until the elements at the far right of the table have completely full outer energy levels , so these elements are very stable and unreactive
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While all of the alkali metals react in similar ways As a result of the single electron in their outer energy level , there's some definite trends in reactivity which can be only explained by looking in more detail at the structure of the atoms
Reactivity increases when we descend the group because the atoms get bigger , so the electron is held less tightly by attraction to the positive nucleus because it is screened by other other full energy levels of electrons . This means the outer electron is lost more easily , so the element is more reactive
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As we go down group 1 why does the density increase
Because the atoms get bigger
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Why do melting points and boiling decrease as we go down group 1
Because the metallic bonds between the Electrons and the positive nuclei get less as the atoms hey larger
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The patterns of behaviour of the elements in group 7 can be explained by the arrangement of electrons in their highest occupied energy level . The trend for the halogens is the opposite to that for the alkali metals .
Going down the group the elements become less reactive because electrons are gained , for ionic or covalent bonding , less and less easily . This is because the larger the atom becomes , the more full energy levels of electrons there are screening the outer electrons from the attractive positive force of the nucleus . This means that the tendency to attract electrons gets less and less
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