The periodic table

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The periodic table por Mind Map: The periodic table

1. Metals

1.1. Group II

1.1.1. Physical properties

1.1.1.1. Melting and boiling point (no observable trend)

1.1.2. Chemical properties

1.1.2.1. Ionization energy decreases down the group

1.1.2.2. Reactivity increases down the group

1.1.2.3. Electronegativity decreases down the group, electron affinity becomes less negative

1.1.2.4. Less reactive than Group ! elements because group !! elements will have 2+ charge when forming ions. Successive ionisation energy increases. It requires more energy to take away 2 electrons.

1.2. Group I

1.2.1. Physical properties

1.2.1.1. Density (no observable trend)

1.2.1.2. Melting and boiling points decrease down group

1.2.1.2.1. Down the group, the number of electron shells increase, hence the atomic size increases. THe atoms in a metal are held together by attractive forces of the nucleus on the delocalized valence electrons. As the atomic size increases, the distance between the nucleus and the delocalized electrons increases. As a result, attractive forces are weaker. The atoms are more easily pulled apart to become a liquid/gas.

1.2.1.3. Soft

1.2.1.3.1. The softness of alkali metals has to do with metallic bonding. For alkali metals, the s orbital is only partially filled. This means that the bonds between each atom are weak because only a cloud of s-orbital electrons are holding them together. As we move right across the periodic table the strength of metals reach a maximum at about group 7-8. This is because at this maximizes the amount of unpaired electrons that participate in the electron cloud that holds metallic bonds together. As we proceed further right (toward Au) the bonds become weaker because the bonding and anti-bonding orbitals begin to fill and pair up. This means these electrons do not participate in the electron cloud of metallic bonding. Thus a weaker bond (softer metal) is formed.

1.2.2. Chemical properties

1.2.2.1. Ionization energy decreases down the group

1.2.2.1.1. Down the group, each successive member has an additional occupied principal quantum shell. Increase in screening effect and distance between the valence electrons and nucleus outweighs increase in nuclear charge. Thus the effective nuclear charge decreases and electrons require less energy to be removed.

1.2.2.2. Reactivity increases down the group

1.2.2.2.1. Down the group, as the first ionisation energy decreases (a result of the increase in atomic radius), reactivity increases as it requires less energy for the single valence electron of the Group 1 Elements to be donated during reactions. Group 1 Elements are generally very reactive due to low ionisation energies and larger atomic radii.

1.2.2.3. Electronegativity decreases down the group, electron affinity becomes less negative

1.2.2.3.1. Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons. As each successive member of the group has an additional occupied principal quantum shell, the screening effect and distance between valence electrons and the nucleus increase. Thus valence electrons experience less attraction toward the nucleus. Electronegativity decreases down the group as atoms have less and less tendency to attract electrons. Electronegativity of group I elements is low because of larger atomic radius compared to across the group.

2. Terms

2.1. Ionization energy is the energy change from losing one electron

2.2. Electron affinity is the energy change from gaining one electron

2.3. Electronegativity is a unitless system that assigns the most electronegative atom, F, a value of 4, and the least, Cs, with a value of 0.7. All values of other elements lie in between. It measures the tendency of an atom to attract a bonding pair of electrons.

3. Non-metals

3.1. Group VII

3.1.1. Physical properties

3.1.1.1. Melting and boiling point increase down the group. Atoms are bigger moving down the group, molecules (F2,Cl2 etc) are bigger and mass increases, thus van der Waals dispersion forces are stronger. There are more electrons which can move around and cause induced dipoles, thus there are strong intermolecular forces and more energy is needed to turn them into liquid/gas.

3.1.1.2. Colour of element gets darker

3.1.1.3. Solubility is low and gets lower down the group

3.1.2. Chemical properties

3.1.2.1. Ionization energy decreases

3.1.2.2. Electronegativity decreases, electron affinity becomes less negative, reactivity decreases

3.1.2.2.1. Down the group, electrons are found in increasingly high energy levels aod are further away from the nucleus. Increased shielding effect and distance from nucleus outweighs increase in nuclear charge and thus effective nuclear charge decreases. Valence electrons experience weaker forces of attraction.

3.2. Group VIII

3.2.1. Unreactive

3.2.1.1. Except for Xenon

3.2.1.1.1. The heavier noble gases have more electron shells than the lighter ones. Hence, the outermost electrons experience a shielding effect from the inner electrons that makes them more easily ionized, since they are less strongly attracted to the positively-charged nucleus. This results in an ionization energy low enough to form stable compounds with the most electronegative elements, fluorine and oxygen. (credit Beatrice)

3.2.2. Melting and boiling points increase down the group