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.
1 Vitamin D deficiency may also hamper the growth of the fetus. 2  Very low vitamin D in the body can be very dangerous. 3  Its symptoms may be related to cardiovascular diseases, cognitive impairment, arthritis, diabetes, hypertension, multiple sclerosis, etc.