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Physical Science Moles

Physical Science Moles. Atomic number- number of protons in that atom Represented by “Z” Ex) Z=11 Mass number- number of protons and neutrons Represented by “A” Ex) A=19. Calculating # of neutrons. Mass number (A) : - Atomic number (Z): ______________________ Number of neutrons:.

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Physical Science Moles

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  1. Physical ScienceMoles

  2. Atomic number- number of protons in that atom • Represented by “Z” • Ex) Z=11 • Mass number- number of protons and neutrons • Represented by “A” • Ex) A=19

  3. Calculating # of neutrons Mass number (A) : - Atomic number (Z): ______________________ Number of neutrons:

  4. Average atomic mass • An element’s average atomic mass is a weighted average of the masses of its naturally occurring isotopes. • Unit : amu

  5. Properties of Metals • Shiny, malleable, ductile, good conductors of heat and electricity • Alkali metals-react violently with water • (very reactive b/c has 1 valence electron Na+) • Alkaline earth metals- • (reactive usually 2 valence electrons Mg 2+) • Transition metals- not as reactive Au, Ag will form cations (ex. Au 3+ ) • Semiconductor can conduct under certain conditions

  6. Properties of Nonmetals • All except for hydrogen are found on the right side of the periodic table. • Can be solids, liquids, gases • solids are usually dull, brittle and poor conductors of electricity and heat.

  7. Nonmetals • Halogens – very reactive, generally accept electrons Cl- , F-, I- • Noble Gases- exist as single atoms instead of molecules. Generally do not react because s and p orbitals are full. • Ex) Ne, Ar, He

  8. Moles • Return to the metric system!!! • Mole-abbreviated mol • A collection of a very large number of particles about • 602 213 670 000 000 000 000 000=??? • Avagadro’s constant- the number of particles in 1 mol of a pure substance

  9. Why 6.022x10 23 ? • The mole is defined as the number of atoms in 12.00 g of carbon-12. • Experiments show that 6.022x10 23 is the number of carbon-12 atoms in 12.00g of carbon-12 • One mole of carbon consists of 6.022x10 23 carbon atoms with an average atomic mass of 12.01 amu

  10. Molar mass • The mass in grams of 1 mol of a substance. • 1 mol of carbon-12 atoms has a molar mass of 12.00g. • But a mole of an element will usually include atoms of several isotopes. • So the molar mass of an element is the same as its average atomic mass in amu. • Carbon is 12.01amu, one mole of carbon has a mass of 12.01g

  11. Conversion factors • A ratio derived from the equality of two different units and that can be used to convert from one unit to another Amount (mol)Mass g amount (mol)x molar mass of element 1 mol of element Mass g Amount (mol)

  12. Examples • What is the mass of 5.50 mol of iron? • Using periodic table, find iron • Average atomic mass = amu • So molar mass = g/mol Fe • Now, set up problem 5.50mol Fe x 55.85 g Fe = 307 g Fe 1 mol Fe

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