Understanding Biology: What are Matter, the Periodic Table, Atomic Structure, Isotopes

In the biology world, matter can be a difficult subject to understand. By definition, matter refers to anything that takes up space and has mass. It can exist as a solid, a liquid or a gas. All matter is composed of elements, or substances that can't be broken down to other substances without using ordinary chemical methods. Matter in turn comprises elements, which are organized in a specific manner on the periodic table. Additionally, atomic structure is a complex subject that plays an important role in the world of elements.

Matter is made up in a specific way known as atomic structure. The atomic theory states that all elements must be made up of atoms. Atoms are made up of a different amount of protons, neutrons, and electrons. These atoms all have their own chemical symbol, such as H for hydrogen. These atoms all have different characteristics. Protons have a positive charge and are found in the nucleus. Neutrons have no electrical charge and are also found in the nucleus. Electrons, on the other hand, are found outside of the nucleus and have a negative charge. Because all of the elements have different amounts of these three things, they have different atomic masses. This mass depends on the number of neutrons and protons within the nucleus. Additionally, the atomic number tells how many protons the element has.

All of these different elements make up the periodic table. They are grouped according to shared characteristics. They are arranged by rows known as periods, and by columns, known as groups. This can be difficult to understand for some, especially when isotopes are introduced. An isotope in an element that has the same atoms as another element, but has a different number of neutrons, thus making them unstable. Additionally, they can decay and emit radiation.

Electrons are arranged based upon their energy levels. The octet rule states that an atom is stable if it has eight electrons in its valence shell. These electrons are constantly moving and fill up different shells. For example, two electrons fill the first shell and eight fill each additional shell. The valence shell is the outermost shell. These atoms can trade electrons; they can either give them up, take them in, or share them in order to meet this rule of eight. This arrangement essentially decides the chemical properties of the atom that they are a part of.