LearnScience

  The menstrual cycle is complex and controlled by many different glands and the hormones that these glands produce. The four phases of the menstrual cycle are menstruation, the follicular phase, ovulation and the luteal phase. Common menstrual problems include heavy or painful periods and premenstrual syndrome (PMS). Knowing when in the menstrual cycle a woman is most likely to conceive can increase the chance of pregnancy. The average length of the menstrual cycle is 28–29 days, but this can vary between women and from one cycle to the next. The length of your menstrual cycle is calculated from the first day of your period to the day before your next period starts. Girls get their first period (menarche), on average, between the ages of 11 and 14 years. By this stage, other sexual characteristics have developed, such as pubic hair and budding breasts. To watch the video, click and follow the link below https://youtu.be/ajWy7LBk9Wk

 Electronic configuration is the arrangement of electron on the shell around the nucleus.  Niel Bohr 1913 posits that the electrons in an atom revolve around the nucleus. Niels Bohr (1913) suggested that electrons revolve round then ucleus on shells or orbits that contains the proton and the neutron  The shells are designated with alphabets from the innermost as K,L,M,N,O, etc  The shells are associated with defined energy content with K shell having the lowest energy content  The shells can also be represented with energy level (n) where K,L,M,N,O are designated as n=1,2,3,4,5  Using the formula 2n², where n is the shell number; the maximum number of electron a shell will contain can be calculated.  K- Shell with n is 1 will contain a maximum of two electrons.i .e. 2x1² =2, when n is 2, M-shell become 2x2²= 8 etc