Properties of Atoms

Physical Science - Middle School

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Isotopes of Carbon Electron Dot Diagram H C O H H O H H O Na Cl Na+ Cl Carbon-12 6 neutrons Carbon-13 7 neutrons Carbon-14 8 neutrons Sodium atom Hydrogen atom Oxygen atom Water molecule Chlorine atom Ionic compound - sodium chloride (salt) Cl- Na+ Crystal structure of salt (NaCl) Proton Neutron covalent bonds nucleus Carbon atom cloud of electrons The Atom Atoms are the basic building blocks of matter that make up everything around us. A pencil, the air, even your body is made up of atoms! There are 90 naturally occurring kinds of atoms. Scientists in labs have been able to make about 25 more. An atom is the smallest part of an element that has all the properties of that element. Particles of an Atom The modern atomic model, suggests that an atom has two particles in the nucleus, a proton which carries a positive charge and a neutron or neutrally charged particle. Surrounding the nucleus is an electron cloud with electrons which carry a negative charge, moving in various directions. The atomic mass number is the sum of the protons and neutrons in the nucleus of an atom. The number of protons is the atomic number of that atom. How Do Atoms Differ? Atoms of the same element can have different numbers of neutrons. Such atoms with the same number of protons and a different number of neutrons are called isotopes. For example, the three isotopes of Carbon have the same number of protons (or the same atomic number) and electrons but they differ in their number of neutrons and thus have a different atomic mass. Valence Electrons & Bonding Electrons surrounding the nucleus are organized in energy levels. An electron that is in the outermost energy level of an atom is a valence electron. A valence electron determines an atom’s chemical properties and whether an atom will form bonds. A bond is the force that joins two atoms together forming a new substance. Ionic Bonds An ionic bond is formed when one or more valence electrons are transferred from one atom to another. Covalent Bonds A covalent bond is formed when atoms share one or more pairs of electrons. An atom’s valence electrons are represented by dots placed around the symbol of an element. O H H transfer of electron Particle Proton Neutron Electron p+ n e- 1+ 0 1- 1 1 1 1,836 Symbol Charge Particles in an Atom Relative Mass (amu) Model C 6 Carbon Element name Symbol Atomic number Atomic mass 12 © Copyright NewPath Learning. All Rights Reserved. 94-4803 www.newpathlearning.com Properties of Atoms
Carbon-12 Carbon-13 Carbon-14 H H O H H O Water molecule Na Cl Na+ Cl Ionic compound - sodium chloride (salt) Isotopes of Carbon \|xiBAHBDy01805mzV The Atom What are atoms? ______________________________________ _____________________________________________________ _____________________________________________________ _____________________________________________________ Particles of an Atom The modern atomic model, suggests that an atom has two particles in the ____________________, a ____________________ which carries a positive charge and a ____________________or neutrally charged particle. Surrounding the nucleus is an electron cloud with ____________________ which carry a ____________________ charge, moving in various directions. The ________________________________________ is the sum of the ____________________and ____________________in the nucleus of an atom. ____________________________________ is the ___________________________ of that atom. How Do Atoms Differ? What are isotopes? ___________________________________ ____________________________________________________ ____________________________________________________ ____________________________________________________ ____________________________________________________ Valence Electrons and Bonding Electrons surrounding the nucleus are organized in ____________________ ____________________ . An electron that is in the outermost energy level of an atom is a ____________________ ____________________ . A valence electron determines an atom’s ____________________ ____________________ and whether an atom will form ____________________ . A ____________________ is the force that joins two atoms together forming a new substance. Ionic Bonds How do ionic bonds form? _______________________________ _______________________________ _______________________________ Covalent Bonds How do covalent bonds form? ____________________________ ____________________________ ____________________________ Electron Dot Diagram H C O An atom’s valence electrons are represented by dots placed around the symbol of an element. O H H C 6 Carbon 12 Key Vocabulary Terms atom atomic mass atomic model atomic number charge chemical bond covalent bond electron electron cloud element energy level ionic bond isotope negative charge neutron nucleus particle positive charge proton valence electron Carbon atom Number of neutrons Number of neutrons Number of neutrons © Copyright NewPath Learning. All Rights Reserved. 94-4803 www.newpathlearning.com Properties of Atoms