The simple view of the bonding in methane You will be familiar with drawing methane using dots and crosses diagrams, but it is worth looking at its structure a bit more closely. There is a serious mis-match between this structure and the modern electronic structure of carbon, 1s 2 2s 2 2p x 1 2p y 1.
Lack of sun exposure: Lack of sun exposure is a major cause of low vitamin d level especially if you live in the northern us. Less likely would be lack of vitamin d in food, but also a possibility if you are on a very restrictive diet.
Some studies show that low blood levels of vitamin D may raise the risk of chronic (long-term) health problems, and that getting more vitamin D may lower those disease risks. Health problems that may be linked to low vitamin D include these, among many others: 1  Some cancers. 2  Heart disease. 3  Diabetes (high blood sugar).