Atomic Number: Symbol - Mr. Sault's Classroom



Review of Atomic ModelHow does the modern atomic theory describe the parts that make up the atom? Atomic Number: Periodic TableAtomic number : number of protons in the nucleus. This number is found above element on a periodic table.Atomic Number: SymbolThe atomic number of an element is usually written on lower left corner of symbol.6266626129836Protons and NeutronsTwo particles in the nucleus: Protons have a positive charge. Neutrons do not have a charge.Neutron NumberThe following table shows the most common number of neutrons found in an element.1327996109309Mass Number5914390-9384Mass number refers to the total number of protons and neutrons. Example:fluorine: 9 protons 10 neutronsAtomic number is 9. Mass number is 9 + 10 = 19Mass Number: SymbolThe mass number is written on upper left corner of element.Electrons Electrons have a negative charge and move outside the nucleus.The number of electrons is equal to the number of protons in a neutral atom.This lithium atom has3 protons and 3 electrons. Atomic Mass579120021602Atomic mass is stated in units called atomic mass units (amu). The symbol for 1 amu can be a “u ” or a ? .6The amu is based on 12 C.61 amu is defined as 1/12 the mass of 12 C. Atomic Mass Periodic TableThe atomic mass is found below the symbol for an element on the periodic table.Atomic Mass DefinedThe mass of 126C is said to be 12 amu. One atomic mass unit6(amu) is defined as being 1/12 the mass of 12 C. Hydrogen has a mass of 1 ? (1/12 the mass of 126C).Helium has a mass of 4 ?(4/12 the mass of 126C).Masses of ParticlesA proton is a “heavy” particle. It mass a mass of 1 ?.A neutron is also a “heavy” particle. It mass a mass very close to 1 ?.3728720273063An electron is very very light. It has a mass of about 1/1837 ? , so sometimes we say that it has a mass of 0 ?(even though it does have some mass).ChecklistUse the modern atomic theory to describe the meaning of the terms atomic number, mass number, atomic mass.BUsing the form A X, write the proper symbol for an element.Predict the number of protons, electrons, and neutrons knowing the atomic number and mass number of an atom.State the charge, location, and mass of the subatomic particles.20447001234761968500202395uraniumuranium ................
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