Atomic Structure Isotopes Atomic Structure particle proton symbol

Atomic Structure Isotopes

Atomic Structure particle proton symbol p+ location nucleus charge 1+ mass 1 amu neutron no nucleus 0 1 amu No charge electron e- Electron cloud 1 - 1/1840 amu

Matter Atoms nucleus Neutrons protons electron cloud = electrons (in a neutral atom) • The number of protons in an atom equals it’s atomic number • Every atom has a unique atomic number • Since electrons are easily gained or lost they determine the overall charge of an atom

Isotopes • Atoms with the same number of protons but different numbers of neutrons • Another way to say – atoms of the same element with different numbers of neutrons • An elements mass number is the number of protons plus the number of neutrons • REVIEW: to determine the number of neutrons subtract the atomic number from the mass number • Mass # – atomic # = # of neutrons

Isotopes of Lithium

Isotopic symbols

Isotopic symbols NOTE: Unlike on the periodic table where the atomic number is at the top of the box and the average atomic mass is at the bottom in isotopic symbols the mass number is at the top and the atomic number is at the bottom. If X is Hydrogen and its mass number is 2 then the isotopic symbol would be 2 H 1

Isotopic symbols If X is Fluorine and its mass number is 20 then the correct isotopic symbol is Fluorine – 20.

If the atom has a charge the charge is written to the upper right side of the symbol. If the charge is either negative or positive 1 the 1 is not written but understood to be 1.

Determine the number of neutron in each isotope 1. 238 – 92 = 146 neutrons 2. 84 – 36 = 48 neutrons 3. 35 – 17 = 18 neutrons 4. 14 – 6 = 8 neutrons