Atomic Structure

The Atom

Proton Positively charged subatomic particle Symbol: p+ Relative Mass: 1 Charge: +1 Location: nucleus

Neutron Subatomic particle with no charge Symbol: n0 Relative Mass: 1 Location: nucleus

Electron Negatively charged subatomic particle Symbol: e− Relative Mass: 0 Charge: −1 Location: outside the nucleus

Atomic Variation

Variation in the # of protons changes the element

Ions Variation in the number of electrons Anion Cation gain of electrons overall charge is negative lose of electrons overall charge is positive 11 protons 12 neutrons 11electrons 10 electrons Sodium atom Sodium ion 1+ Na 1− F

C C C Isotopes 12 6 13 6 14 6 Variation in the number of neutrons Atoms that have the same number of protons but have a different masses Ex: 3 isotopes of carbon: 12 6 C 13 6 C 14 6 C

X Nuclide Symbol A ±# Z Atomic Number Mass Number the number of protons in an atom Identifies element Symbol: Z Represents the total number of protons and neutrons in the nucleus (p+ + n0) Symbol: A Charge Chemical Symbol States whether electrons were gained or lost from the neutral atom Helps indicate chemical bonding Symbol: ± # Short-hand abbreviation for the element name Only first letter should be capital

Naming Isotopes State the element name or symbol followed by a hyphen and the mass number Ex: Carbon—14

Practice How many protons, neutrons and electrons are in Cobalt—59? Write the nuclide symbol and name of an isotope that has 15 protons, 17 neutrons, and 18 electrons. Write the nuclide symbol of an isotope that has 18 protons, 22 neutrons, and 18 electrons.

Atomic Mass Mass of a single atom in atomic mass units (amu)

Average Atomic Mass the weighted average of all atoms of an element (includes all naturally occurring isotopes) Formula: Average Atomic mass of an element = ( % abundance of Isotope #1 x mass Isotope #1 ) + Isotope #2 …

Example 1 Silver has two naturally occurring isotopes. Ag-107 has an abundance of 51.82% and mass of 106.9 amu. Ag-109 has a relative abundance of 48.18% and a mass of 108.9 amu. Calculate the average atomic mass of silver.

Example 2 Rubidium is a soft, silvery-white metal that has two common isotopes, Rb and Rb. If the abundance of 85Rb is 72.7% with an atomic mass of 84.91 amu and the abundance of 87Rb is 27.8% with an atomic mass of 86.91 amu, what is the average atomic mass of rubidium? 85 37 87 37