Nursing Preparation Study Guide

Nursing Preparation Study Guide of 173 The protons and neutrons inside an atomic nucleus are not fundamental particles. That is, they can be divided into still smaller pieces. Protons and neutrons are known as hadrons, which is a class of particle made up of quarks. Quarks are a fundamental particle. There are two distinct types of hadrons – baryons and mesons – and both protons and neutrons are baryons, meaning they are both made up of a combination of three quarks. Besides, being hadrons, protons and neutrons are also known as nucleons because of their place within the nucleus. Protons have a mass of around 1.6726 × 10-27 kg and neutrons have a nearly identical mass of 1.6929 × 10-27 kg. Both particles have a ½ spin. The number of protons inside an atomic nucleus determines which element the atom comprises. An element with only one proton, for instance, is hydrogen. An element with two is helium. One with three is lithium, and so on. No element (except for hydrogen) can exist with only protons in its nucleus. Atoms need neutrons to bond the protons together using the strong force. In general, atoms have an equal number of protons and neutrons in their nuclei except for hydrogen. Atoms with an uneven number of protons and neutrons are called isotopes. Isotopes have all the same chemical properties as their evenly balanced counterparts, but their nuclei are not usually as stable and are more willing to react with other elements. Two deuterium atoms, which are hydrogen isotopes with one proton and one neutron in their nucleus rather than only one proton, will fuse much more readily than two regular hydrogen atoms. Nearly all of an atoms’ mass is within its nucleus. Outside the nucleus is a lot of empty space occupied only by a few, tiny electrons. Electrons were once viewed as orbiting an atom like planets orbit the sun. We now know that this is wrong in several ways. For one, electrons do not really “orbit” in the sense we know. At the quantum level, no particle is really a particle, but is actually both a particle and a wave simultaneously. Heisenberg’s uncertainty principle looks at this odd truth about reality and says you cannot watch an electron orbit the nucleus as you would watch the Earth orbit the sun. Rather, you should observe only one of the electron’s physical characteristics at a time, either viewing it as a particle in a fixed position outside the nucleus or as a wave encircling the nucleus like a halo. Additionally, planets orbiting their stars can orbit at any distance they want. In fact, every object in our solar system has an elliptical orbit, meaning that they all move in an oval shape, getting closer and farther from the sun at various points. Electrons cannot do this under any circumstances. Atoms have what are known as electron shells, which are the levels that an electron is able to inhabit. Between these shells, electrons cannot exist; instead, they jump from one to the next instantaneously. Each electron shell can hold a different number of atoms. When a shell fills up, additional electrons fill the outer shells. The outermost shell of any atom is called the valence shell, and it is the electrons in this shell that interact with the electrons of other atoms. The important thing about the valence shell is that each electron shell has a specific number of electrons that it can hold, and it wants to hold that many. ©2018 Achieve Test Prep Page 152