The Atom http://www.youtube.com/watch?v=Uy0m7jnyv6U

Subatomic Particles A. Atomic Number B. Mass Number and Isotopes C. Electrons and Ions D. Nuclear and Hyphenation Notation E. Average Atomic Mass Weighing and Counting Atoms A. Mole Atoms B. Mole Mass C. Mass Atoms

Subatomic Particles A. Comparing Particles Relative mass Actual mass (g) Name Symbol Charge Electron e- -1 9.11 x 10-28 Proton p+ +1 1amu 1.67 x 10-24 Neutron n0 1amu 1.67 x 10-24

Subatomic Particles B. Atomic Number and Mass Number 1. the number of protons in the nucleus of an atom a. identifies the element b. no two elements have the same atomic number Ex. C is 6, N is 7 and O is 8 carbon nitrogen oxygen

Subatomic Particles B. Atomic Number and Mass Number a. the number of protons plus neutrons in the nucleus of an atom b. mass number is very close to the mass of an atom in amu (atomic mass units) c. two atoms with the same atomic number but different mass number are called isotopes 1) (mass #) – (atomic #) = #n 0

X Subatomic Particles C. Nuclear Notation Nuclear Notation is one method for depicting isotopes of an element contains the symbol of the element, the mass number, and the atomic number Mass number X Atomic number

Na 23 11 Subatomic Particles C. Nuclear Notation How many protons? How many neutrons? How many electrons? 23 Na 11

Subatomic Particles C. Hyphen Notation 1. Element symbol or name – mass # 2. EXAMPLES a. Fluorine-19 b. C-14 c. U-238

Subatomic Particles D. Ions 1. Electrons and Ions a. For neutral atoms, #e- = #p+ b. If there are more electrons, a negative ion forms (anion) c. If there are less electrons, a positive ion forms (cation) http://www.youtube.com/watch?v=WWc3k2723IM For now, we will work only with neutral atoms

The modern table Elements are still grouped by properties. Similar properties are in the same column. Order is in increasing atomic number. Added a column of elements Mendeleev didn’t know about. The noble gases weren’t found because they didn’t react with anything.

Trend of periodic table group1 group2 group13 group14 group15 group16 group17 group18 H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar - K Ca Boiling point: group1 group2 group13 group14 group15 group16 group17 group18 21K 4K 1600K 2780K 2800K 4620K 77K 90K 85K 27K 1162K 1390K 2600K 2950K 553K 718K 239K 87K 1030K 1760K

Melting Point group1 group2 group13 group14 group15 group16 group17 group18 14K 0K 453K 1560K 2348K 3823K 63K 54K 53K 24K 379K 923K 933K 1687K 317K 388K 171K 83K 336K 1115K

Horizontal rows are called periods There are 7 periods

The elements in the A groups are called the representative elements

The group B are called the transition elements These are called the inner transition elements and they belong here

Group 1A are the alkali metals Group 2A are the alkaline earth metals

Group 7A is called the Halogens Group 8A are the noble gases

Subatomic Particles D. Formation of Ions Examples of Ions Atom loses electrons Atom gain electrons and form cations and forms anions Cations (+ ions) Anions (- ions) K+ Br- Ca2+ O2- Al3+ N3-

ions

D. Formation of Ions From Atoms Na loses an electron and forms a cation Na – e- --> Na+ Cl gains an electron and forms an anion Cl + e- --> Cl-

Subatomic Particles D. Changing Number of Particles 1. You can never change the number of protons and have the same element 2. If you change the number of neutrons in an atom, you get an isotope 3. If you change the number of electrons in an atom, you get an ion

Mass of Atoms A. Atomic Mass 1. Mass of an atom a. too small to measure in grams b. use relative mass (amu) 1) atomic mass unit 2) 1 amu is defined as 1/12 the mass of one C-12 atom http://www.youtube.com/watch?feature=player_detailpage&v=nmjFKliv09E

IV. Mass of Atoms B. Average Atomic Mass 1. weighted average mass of all known isotopes a. weighted means that the frequency of an isotope is considered b. mass of each isotope is multiplied by its percent occurrence in nature – then masses of all isotopes is added to get the average atomic mass

IV. Mass of Atoms C. The Mole and Molar Mass 1. measures the amount of substance a. 1 mole = 6.02x1023 (Avogdro’s #) of particles (atoms, molecules, ions, electrons) b. standard – 1mole is the number of atoms in 12g of C-12 isotope 2. Molar mass – mass in grams of one mole (mol) of any substance a. numerically equal to atomic mass in amu b. unit is grams/mol

What is average atomic mass? Average atomic mass is the weighted average of the atomic masses of the naturally occurring isotopes of an element

Calculating a Weighted Average Example A box contains two size of marbles. If 25.0% have masses of 2.00 g and 75.0% have masses of 3.00 g what is the weighted average? (.250) (2.00) + (.750) (3.00) = .500 + 2.25 = 2.75g

Calculating Average Atomic Mass EXAMPLE Boron has two isotopes: B-10 (mass 10.013 amu) 19.8% abundance B-11 (mass 11.009 amu) 80.2% abundance Calculate the average atomic mass. (.198) (10.013) + (.802) ( 11.009) = 1.98 amu + 8.83 amu = 10.81 amu

Calculating Average Atomic Mass Calculate the average atomic mass of Mg. Isotope 1 - 23.985 amu (78.99%) Isotope 2 - 24.986 amu (10.00%) Isotope 3 – 25.982 amu (11.01%) (23.985)(.7899)+(24.986)(.1000)+(25.982)(.1101) 18.95 amu + 2.498 amu + 2.861 amu = 24.31 amu

Average Atomic Mass Helium has two naturally occurring isotopes, He-3 and He-4. The atomic mass of helium is 4.003 amu. Which isotope is more abundant in nature? He-4 is more abundant in nature because the atomic mass is closer to the mass of He-4 than to the mass of He-3.

Calculating Average Atomic Mass Process Multiply %occurrence x mass of isotope Add products for each isotope isotope occurrence isotope occurrence Ex. X- 40 (30.0% ) X-30 (70.0%) (40 x .300) + (30 x .700) = 12 + 21 = 33 amu

Isotopic Pennies – number of pre and post 1982 a. Let X be the number of pre-1982 pennies b. Let 10-X be the number of post-1982 pennies c. (X)(3.1g) + (10-X)(2.5g) = mass of 10 pennies pre-82 post-82 EXAMPLE (Mass of a sample of pennies is 31.0g) (X)(3.1g) + [(10-X)(2.5g)] = 31.0 g 3.1X + 25 - 2.5X = 31.0g .6X + 25 = 31.0g .6X = 6.0g X = 6.0g/.6 X = 10 pre-82 pennies 10-X = 0 post-82 pennies

Isotopic Penny Lab- Average Atomic Mass Calculate percent of pre-82 and post-82 pennies # of pre-82 pennies x 100% # post-82 pennies x 100% 10 10 Calculate the average atomic mass of coinium (% pre-82)(3.1g) + (% post-82)(2.5) = average atomic mass

The Mole What is a mole in chemistry? What conversion factors are associated with the mole? Types of conversions involving mole equalities

What is a Mole? What are mole equalities A mole is equal to 6.02 x 1023 particles Particles can be atoms, molecules or ions 6.02 x 1023 is Avogadro's Number Mole Equalities - 1 mole = molar mass - 1 mole = 6.02 x 1023 particles

Mole Conversions [mass-mole-atoms] Type Equality Used 1. MOLES  MASS 2. MASS  MOLES 1 mole= molar mass (g) 3. MOLES  ATOMS 4. ATOMS  MOLES 1 mole = 6.02 x 1023 atoms 5. MASS  ATOMS 1 mole = 6.02 x 1023 atoms 6. ATOMS MASS 1 mole = molar mass (g)

Mole Calculations Using Conversion Factors 1 mole molar mass 6.02 x 1023 1 mole PARTICLES <----> MOLES <----> MASS 6.02 x 1023 1 mole 1 mole molar mass

Solving Mole Problems EXAMPLES 1.00 mole of He = 4.00 g. 2.00 mol He X 4.00g He = 1 1 mole He 8.00 g He

EXAMPLES 1.00 mole He = 6.02 X 1023 atoms 2.00 mole He = ________atoms He 2.00 mole He x 6.02 x 1023 atoms He = 12.04 x 1023 1 1 mole He 1.20 x 1024 atoms He 16.00g He = _____ moles He 16.0 g He x 1 mole He = 1 4.00 g He 4.00 moles He

EXAMPLES 3.01 X 1023 atoms He = _____ moles 3.01 x 1023 atoms He x 1 mole He = 1 6.02 x 1023 atoms He .500 mol He 8.00g He =______atoms He 8.00 g He x 1 mole He x 6.02 x 1023 atoms He = 1 4.00g He 1 mole He 12.04 x 1023 atoms He = 1.20 x 1024 atoms He

Sample Problems Moles to mass. Find the mass of 3.50 moles of carbon. Mass to Moles How many moles of carbon are contained in 60.0 g of carbon? Moles to Atoms How many atoms of carbon are found in 4.00 moles of carbon?

Sample Problems Atoms to Moles How many moles of carbon are represented by 1.806 x 1024 atoms of carbon? Mass to Atoms How many carbon atoms are found in 36.0g of carbon? Atoms to Mass What is the mass of 1.204 x 1024 atoms of carbon?

More Sample Problems 2.00 moles of Cu = atoms of Cu 60.0 grams of C = moles of C 3.00 x 1023 atoms He = moles of He 2.50 moles Al = grams of Al 28.0 grams N = atoms of N 1.80 x 1023 atoms Mg = grams of Mg

Mole Calculations (Mass of Helium is 4.00 ) 1. 1.00 mole of helium = 4.00g 2.00 mole of helium = 8.00g 1.00 mole of helium = 6.02 x 1023 atoms 2.00 mole of helium = 1.20 x 1024 atoms 16.0g of helium = 4.00 mol 3.0l x 1023 atoms of helium = .500 moles 8.00g of helium = 1.20 x 1024 atoms.