The document provides information about atoms and their structure. It defines key terms like protons, neutrons, electrons, nucleus and isotopes. It explains that the number of protons determines the element and distinguishes one atom from another. The mole is also defined as 6.02x10^23 particles and is used to measure amounts of substances on a macroscopic scale. Formulas are given to calculate molar mass and empirical formulas.

1. Chapter 3 Atoms: the Building Blocks of Matter

4. Atomic Structure Here are the basics; you need to know these. 1 H 1.0076 Hydrogen Atomic Number ( Z ) : the number of protons (p + ) Atomic Mass : the number of protons (p + ) + the number of neutrons (n 0 ) ▪ measured in atomic mass units (amu) which is one twelfth the mass of a carbon-12 atom. ▪ the mass of electrons (1/1860 p + ) is negligible. Number of Neutrons : the atomic mass - the atomic number Atomic Number Atomic Symbol Atomic Mass

5. Lets practice! Find the missing information? 8 15.999 amu O 2 2 He 39.948 amu 18 Ar Neutrons Electrons Protons Atomic Mass Atomic # Element

10. The Mole (aka Avagadro’s Number) : 6.02 x 10 23

13. Examples: 6.02 x 10 23 Ca 2+ Ion Calcium ion 6.02 x 10 23 H 2 O Molecule Water 6.02 x 10 23 N Atom Atomic nitrogen Representative Particles in 1.00 mol Chemical Formula Representative Particle Substance

14. Solve Representative Particles in 1.00 mol Formula Unit Representative Particle Substance Molecule C Carbon Molecule C 12 H 22 O 11 Sucrose Molecule CaF 2 Calcium Fluoride Molecule N 2 Nitrogen gas