Gram Atomic Mass of Chemistry

University:
High School
Course:
High School Chemistry
Academic year:

2020
Views:

172

Pages:

9
Author:

Lispjaitteees

Mass Number The total number of PROTONS and NEUTRONS in the nucleus of ONE atom. Atomic Mass The average of all the MASS NUMBERS of all the NATURALLY occurring isotopes of an element. Where is this number on the Periodic Table? Upper LEFT When a whole number = Mass No. = P+n Average Atomic Mass KEEP THE DECIMALS! Calculate the average atomic mass for Gallium if 60.00% of its atoms have a mass of 68.926 amu and 40.00% have a mass of 70.925 amu. (60.00% x 68.926) + (40.00% x 70.925) = 41.3556 + 28.37 = 69.7256 amu Answer Must be between 2 Mass Values. Calculate the average atomic mass of oxygen. Its composition is 99.76% of atoms with a mass of 15.99 amu, 0.038% with a mass of 17.00 amu, and 0.20% with a mass of 18.00 amu. (99.76% x 15.99) + (0.038% x 17.00) + (0.20% x 18.00) = 15.951624 + 0.00646 + 0.036 = 15.994084 amu Gram Atomic Mass = The quantity of an element whose MASS in GRAMS is EQUAL to its Atomic Mass. Element Atomic Mass (amu) Gram Atomic Mass (g) N-1 14.0067 14.0067 Al- 26.981542 26.98154 Li- 6.941 6.941 The Gram Atomic Mass of any element contains 6.02 x 10²³ Atoms of that element. This number 6.02 x 10²³ is called AVOGADRO'S NUMBER This quantity of any element is also called ONE MOLE 1 Mole = 6.02 x 10²³ Molecules = 1 Gram Atomic Mass (total gram formula mass) Element Gram Atomic Mass Moles Atoms N- 14.0067 1 6.02 x 10²³ Al- 26.98154 1 6.02 x 10²³ Li- 6.941 1 6.02 x 10²³ If the number of moles and atoms are the same, why is the mass of each element different? Each element has a different number of protons and neutrons so each element has a different mass Gram Molar Mass/ Gram Molecular Mass/ Gram Formula Mass The SUM of all the Atomic Masses of all the atoms in one molecule of a compound.