Nursing Preparation Study Guide

Nursing Preparation Study Guide When atoms join, their connecting valence electrons take up two valence shell spots, one on each atom. This means that the fewer electrons an atom has in its valence shell, the more likely it is to interact with other atoms. On the other hand, the more electrons it has, the less likely it is to interact. Additionally, electrons are able to momentarily jump from one electron shell to the next if they are hit with a burst of energy from a photon. When photons hit atoms, the energy is briefly absorbed by the electrons, and this momentarily knocks them into higher “orbits”. The particular “orbit” the electron is knocked into depends on the type of atom, and when the electron gives up its higher energy level, it reemits a photon at a slightly different wavelength than the one it absorbed, providing a characteristic signal of that atom and showing into exactly which “orbit” the electron was knocked. This is the phenomenon responsible for spectral lines in light and is the reason we can tell what elements make up stars and planets simply by looking at them. Unlike protons and neutrons, electrons are a fundamental particle on their own; they are also called leptons. Electrons have a negative charge that is generally balanced out by the positive charge of their atom’s protons. Charged atoms, which have either gained or lost an electron for various reasons, are called ions. Ions, like isotopes, have the same properties that the regular element does; they simply have different tendencies towards reacting with other atoms. Electrons have a mass of 9.1094 × 10- 31 kg and a -½ spin. Element The concept of a chemical element is related to that of a chemical substance. A chemical element is a substance that is made up of a single type of atom. A chemical element is characterized by a particular number of protons in the nuclei of its atoms; this number is known as the element’s atomic number. For example, all atoms containing six protons in their nuclei are atoms of the element carbon, and all atoms with 92 protons in their nuclei are atoms of the element uranium. 9.2.5 The Periodic Table The periodic table contains the known chemical elements displayed in a special tabular arrangement based on their electron configurations, atomic numbers, and recurring chemical properties. The first semblance of a periodic table was by Antoine Lavoisier in 1789. He published a list, or table, of the 33 chemical elements known at that time. He grouped the elements into earths, non-metals, gases, and metals. In the following century, several chemists began looking for a better classification method, which led to the periodic table we use today. Structure of the Periodic Table The standard periodic table is comprised of 18 columns and seven rows that contain the main chemical elements. Under this table is a smaller one – 15 columns by two rows. The periodic table can be broken down into four rectangular blocks: the P block is by the right, S block is left, D block is at the middle, and the F block is underneath that. The elements in the blocks are based on in which sub-shell the last electron resides.

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