75% of the 92 elements in the universe is hydrogen. In this universe, there are 100 billion galaxies and each galaxy has 100 billion stars. Atoms came from the dust of stars since stars compose heavier elements (carbon, nitrogen, etc.) when they explode, therefore we humans are like stardust. Humans are made up of CHONPS, which stands for carbon, hydrogen, oxygen, nitrogen, and phosphorus. Hydrogen, oxygen, nitrogen, and carbon make up over 95% of what we are. The universe’s magic number is 8 because all of the these three elements with the exception of hydrogen, since it is too small, wants 8 electrons in its outer shell.
Light years is not time, but it is a distance of how far light travels in a year. Us humans are not familiar with very large-scales or really small things, like a micrometer which is a millionth of a meter. And so a meter is considered the most comfortable distance for us.
EVERYTHING is made up of things that are smaller. Like the ecosystem is made of organisms, which has organ systems which is composed of organs -> tissues -> cells -> molecules and eventually atoms. Atoms are the smallest units of matter and cannot be reduced. They are made of protons, neutrons and electrons. Atoms join together to make molecules. When different kinds of atoms bond together, they produce compounds.
All the other elements except for Noble Gases need to bond to have 8 electrons. Chemical reactivity depends on the valence electrons of an atom. Noble Gases are like kings and queens that do not have to bond with others since they have a complete outer shell. Therefore, noble gases do not react. On the other hand, other elements need to become satisfied so they build up on relationships with other elements. Hydrogen is into monogamy, which means it bonds with one other element at a time. The bonds between atoms vary in the strength. Ions are made from gaining or losing electrons. In an ionic bond, positive and negative ions are joined together forming a relatively weak bond. Sodium chloride is an example of an ionic bond. Therefore, we humans cannot be made of ionic bonds because we would dissolve in water. Covalent bonds are produced when atoms share electrons in which they produce strong and stable bonds. Lastly, hydrogen bonds are produced between polar molecules when a partially positive atom is attracted to a partially negative atom and they form weak bonds. Carbon is the most versatile element on earth, it has four electrons in its outer shell and is like a “party animal” since it can have 4 relationships at once. Nitrogen gas molecules are the most abundant in the air we breathe in, can form triple bonds.
Electronegativity is the ability of an atom to attract electrons. Chlorine has a high electronegativity and tend to gain electrons from wherever they can get it. Though sodium, has a low electronegativity and has a tendency to lose their outer most electrons. Since chlorine has a high electronegativity and can attack molecules, so you do not want something that contains a lot of chlorine inside your body. Chemical bonds and interaction between the molecules gaining or losing electrons to form more stable combinations are the reason behind why the universe is constantly changing. The whole universe seems like a solid to us, but it is all an illusion from the electrons. Electrons move 1/8 at the speed of light and never stop and makes it a blur and making everything look like a solid.