Some patterns and trend that are present in the periodic table would be
1. electronegativity (from left-to-right it increases across the table)
2. ionization (from left-to right it increases and from bottom-to-top it increases)
3. electron affinity (same as ionization energy)
4. atom radius (increases opposite way; from right-to-left it increases and from top-to-bottom it increases)
5. melting point (higher melting points with metals and lower melting point with non-metals)
6. metallic character (same as atom radius)
<span>The problem has to do with oxidation states of the matter. The oxidation state of oxygen will always be -2 with the exception of peroxides which will have a state of -1. The overall balanced state of chemical compounds will be 0, so the oxidation state of Mn in MnO2 will be +4. The oxidation state of MnO4- will then be +7 to balance out to the negative one charge. The state change from +4 to +7 is 3, thus three electrons have to be lost in order for this to happen; a loss of a charge of -3 results in an increase of charge of 3. Oxidation is always the process of 'losing' electrons.
</span><span>E] MnO2(s) MnO4-(aq</span>
Atoms in covalent bonds do combine so as to be stable. As covalent bond consist non metals e.g O2 in this example each atom has vacance of 2 orbitals/ electrons so shairing electrons result their stability