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21 Cards in this Set
- Front
- Back
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Plum pudding model |
Atom is a ball of positive charge with negative electrons embedded. Jj thompson |
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Alpha scattering experiment |
Scientists got a thinn sheet of gold. Scientists fired tiny particles at the sheet. Most passed through - mainly empty space. Sometimes they were deflected - centre has positive charge. Sometimes it bounced back off - contains alot of mass Nuclear model |
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Bohr |
He improved Rutherfords experiment by showing that electrons have shells |
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Atomic number and mass number |
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What is an isotope |
Atom of an element with different numbers of neutrons |
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What is an ion |
An ion is a charged atom which has lost or gained an electron |
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Mendeleev periodic table |
Arranged elements in order of atomic mass. He sometimes switched the order of elements so they fitted the patterns of other elements in the group. He left gaps for undiscovered elements. |
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What is the difference between mendeleev and modern periodic tables |
Now, elements are arranged in order of atomic number. Mendeleev ordered them in atomic mass. Group 0 wasnt discovered in mendeleev time |
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Group 0 properties (noble gases) |
Very unreactive because it has a full outer energy level and so is stable. Boiling points lower than room temperature. Boiling points increase as relative atomic masses increase(going down group) |
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How does the melting and boiling points of the group 7 elements change as you go down the group |
They increase as you move down the group |
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What happens when a group 7 element reacts with another non metal |
It forms a covalent compound |
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What happens when a group 7 element reacts with a metal |
A ionic compound is formes |
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What happens to the reactivity of elements when you go down the group 7 |
It decreases because the electrons are attracted to the nucleus so if there is less energy shells it will react more. |
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Properties of group 1 elements |
Soft,low melting points,low density, react rapidly with oxygen, chlorine and water. |
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Properties of transition elements |
Hard and strong High melting points High density Much less reactive Form coloured compounds |
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What is conservation of mass |
Mass of products=mass of reactants |
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How calculate moles of an element |
Mass/Ar |
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How to calculate moles of a compound |
Mass/Mr |
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Reacting masses steps |
Work out the moles of calcium. Miles of calcium is equal to moles of calcium sulfate. Rearrange moles equation to get mass |
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Why is it not possible to make 100% yield |
Some of product may be lost when it is being separated. Some of the reactants may react in different ways to the expected result. Reversible reactions s may not go to completion |
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Formula for percentage yield |
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