C3 1 - The periodic table
- Created by: Natalia
- Created on: 11-03-13 19:07
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- C3 1 - The periodic table
- The early periodic table
- Newlands, and then Mendeleev, attempted to classify the elements by arranging them in order of their atomic weights.
- The elements can be arranged in a table so that elements with similar properties are in columns, known as groups.
- The early periodic tables were incomplete and some elements were placed in inappropriate groups if the strict order of atomic weights was followed.
- Mendeleev overcame some of the problems by leaving gaps for elements that he thought had not been discovered.
- It is called a periodic table because similar properties occur at regular intervals.
- Newlands, and then Mendeleev, attempted to classify the elements by arranging them in order of their atomic weights.
- The modern periodic table
- When electrons, protons and neutrons were discovered early in the 20th century, the periodic table was arranged in order of atomic numbers.
- When this was done, all elements were placed in appropriate groups.
- The modern periodic table can be seen as an arrangement of the elements in terms of their electronic structures.
- Elements in the same group have the same number of electrons in the highest occupied energy level.
- When electrons, protons and neutrons were discovered early in the 20th century, the periodic table was arranged in order of atomic numbers.
- Group 1 elements (the alkali metals)
- Metals with low density.
- The first three can float on water.
- React with non-metals to form ionic compounds.
- The metal ion carries a charge of +1.
- The compounds are white solids that dissolve in water to form colourless solutions.
- React with water, releasing hydrogen.
- Form hydroxides that dissolve in water to give alkaline solutions.
- The further down a group an element is...
- The more reactive the element is.
- The lower its melting and boiling point.
- Metals with low density.
- Transition metals
- Compared to the elements in group 1...
- Have higher melting points (except for mercury)
- Have higher densities.
- Are stronger and harder.
- Are much less reactive and so do not react as vigorously with water or oxygen.
- Have ions with different charges.
- Form coloured compounds
- Are useful as catalysts.
- Compared to the elements in group 1...
- Group 7 - the halogens
- React with metals to form ionic compounds in which the halide ion carries a charge of -1.
- The further down an element is...
- The less reactive the element.
- The higher its melting and boiling points.
- A more reactive halogen can displace a less reactive halogen from an aqueous solution of its salt.
- Trends within the periodic table
- The higher the energy level of the outer electrons...
- The more easily electrons are lost.
- The less easily electrons are gained.
- The higher the energy level of the outer electrons...
- The early periodic table
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