132721
Description
Flashcards by eimearkelly3, updated more than 1 year ago
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Created by eimearkelly3
over 11 years ago
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| Question | Answer |
| Elements | Substances that cannot be borken down into simpler materials. |
| Atomic Number | Number of protons |
| Empedocles (Greeks) | Elements are the basic substances from which all other substances are made ; fire, earth, water, air |
| Robert Boyle | Elements are substances that cannot be borken down into simpler materials. Compoumds- cobinations of elements which can be formed from and broken down into these elements. |
| Humphry Davy | electrolysis 1. potassium, sodium 2. barium, strontium, magnesium, calcium |
| Henry Moseley | Nucleus has a positive charge called the ATOMIC NUMBER - led to the arrangement of elements in order of atomic number rather than mass and a more advanced definition : an element is a substance all of whose atoms have the same atomic number. |
| Group | Vertical |
| Period | Horizontal |
| Right of stepped line | Non-metals |
| Left of stepped line | Metals |
| Group 1 | Alkalis |
| Group 2 | Alkaline Earth Metals |
| Group 7 | Halogens |
| Group 8 | Noble Gases |
| Alkali Metals physical/chemical properties | soft, silver metals, low density reactivity increases doen the group, react with water forming hydroxide and hydrogen and with air to form oxide |
| What are alkali metals stored in and why? | Oil - to prevent reaction with atmospheric oxygen or with water |
| Alkaline earth metals physical/chemical properties | silver metals, harder then alkali metals less reactive than corresponding alkali metals, reactivity increase down the group |
| Halogens physical/chemical properties | Non-metals, low melting and boiling points very reactive, reactivity decreases down the group, react with hydrogen giving compounds which dissolve in water to form acidic solutions, react vigorously with sodium and other alkali metals giving white salts |
| Noble Gases | gases at room temperature, boiling point and density increases going down the group least reactive, inert gases |
| Inert Gas | Chemically unreactive |
| Johann Döbereiner | Triads A) Similar chemical properties B) Atomic weight of middle element half way between the other two. |
| John Newlands | Octaves Chemical properties repeat themselves every eighth element when arranged in order of atomic weight |
| Dmitri Mendeleev | He organised his table according to his 'periodic law' : Elements are arranged in order of atomic weight in such a way that elements with similar chemical properties are in the same group. |
| Differences between modern periodic table and Mendeleev's | n order of atomic weight rather than number. No noble gases Gaps for undiscovered elements. He put some elements in reverse order e.g. tellerium and iodine so that the elements would be in the correct order. |
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Empedocles |
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Robert Boyle |
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Humphry Davy |
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Henry Moseley |
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Johann Döbereiner |
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John Newlands |
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Dmitri Mendeleev |
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