8U1 - 5(A) describe the structure of atoms, including the masses, electrical charges, and locations, of protons and neutrons in the nucleus and electrons in the electron cloud; Matter is anything that takes up space. All Matter is composed of tiny particles called ATOMS. Surprisingly, in the entire universe there are only 118 different kinds of atoms. Here on earth, there are approximately 70 different kinds of common atoms. We call them ELEMENTS. Elements are only made up of one kind of atom. The smallest possible element would be one proton and one electron. This is the element hydrogen. The next possible element is 2 protons and 2 electrons. This is the element Helium. Next is Litium, with 3 electrons and 3 protons. The progression of the elements is shown below. Atom the smallest particle into which an element can be divided and still have the properties of that element; consists of protons, neutrons, and electrons atom Smallest particle of an element. electron A tiny, negatively charged particle that moves around the nucleus of an atom Electrons The electrons are moving VERY fast around the nucleus Proton positively charged particle located in the nucleus of an atom Protons determine the identity of the atom. neutron A subatomic particle that has no charge and that is found in the nucleus of an atom nucleus of The protons and neutrons are held atom together in the positively charged nucleus of the atom If the atoms are packed closely together, we have a SOLID IF the atoms are loosely connected to each other, we have a LIQUID If the atoms are not connected at all, we have a GAS Each atom consists of 3 parts: Protons and neutrons in the nucleus, with electrons orbiting in orbitals. atom the basic building block of matter Electron each electron has 1 unit of negative charge • proton Each proton has 1 unit of positive charge neutron A particle without an electrical charge within the atomic nucleus Isotope An atom with the same number of protons and a different number of neutrons from other atoms of the same element. Nucleus The center of an atom that contains the (Atom) protons and neutrons Neutral Atoms are neutral – the number of positive protons is exactly the same as the number of negative electrons, resulting in a net charge of zero. Molecule Groups of two or more atoms held together by chemical bonds octet rule How elements generally prefer to form bonds so as to attain eight electrons in their outer shell Valence An electron in an outer shell of an atom Electrons that can participate in forming chemical bonds with other atoms Argon Valence electrons = ? 8 Potassium Valence electrons = ? 1 Nitrogen Valence electrons = ? 5 8U1 - 5(B) identify that protons determine an element's identity and valence electrons determine its chemical properties, including reactivity; Valence electrons determine how an element will react with other substances. Elements in the same Group / Family have the same number of valence electrons. This is why elements in the same Group / Family have similar properties and reactivites. .