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17 Cards in this Set
- Front
- Back
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How are elements arranged in the periodic table? |
In order of atomic number, so that elements with similar properties are in columns known as groups |
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Why is the table called a periodic table? |
Because similar properties occur at regular intervals |
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Why do elements in the same group have similar properties? |
They have the same number of valance electrons which gives them similar chemical properties |
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Before the discovery of protons, neutrons and electrons how did scientists attempt to classify elements? |
They arranged them in order of atomic weights |
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What was the problem with this? |
The table was incomplete so some elements were placed in inappropriate groups |
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How did mendeleev overcome some of the problems? |
He left gaps for elements he thought hadn't been discovered and changed the order in some places |
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What made it possible to explain that order based on atomic weight wasn't always correct? |
Knowledge of Isotopes |
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The majority of elements are... |
Metals |
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Metals form what type of ions when they react? |
Positive Ions |
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What are elements in group 0 called? |
Noble Gases |
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Properties of Noble Gases |
Unreactive Do not easily form molecules ^due to stable arrangements of electrons Bp increase as you go down the group |
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What is group 1 elements called? |
Alkali metals |
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How many valance electrons do group 1 elements have? |
1 |
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Properties of group 1 |
Reactivity of the elements increases going down the group |
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What are the elements in group 7 called? |
Halogens |
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Properties of halogens |
7 valance electrons Non-metals
Consists of molecules made of pairs of atoms
Down the group : the hight the relative molecular mass, mp and bp Reactivity decreases down the group |
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Displacement |
A more reactive halogen can displace a less reactive halogen from an aqueous solution of its salt |
