DALTON’S ATOMIC THEORY (1808)

1. All elements are composed of atoms, which are 1. All elements are composed of atoms, which are indivisible and indestructible particles.indivisible and indestructible particles.

2. All atoms of the same element are exactly alike; in 2. All atoms of the same element are exactly alike; in particular, they all have the same mass and properties.particular, they all have the same mass and properties.

3. Atoms of different elements are different; in 3. Atoms of different elements are different; in particular, they have different masses and different particular, they have different masses and different properties.properties.

4. Compounds are formed by the joining of atoms of 4. Compounds are formed by the joining of atoms of two or more elements in small whole ratios.two or more elements in small whole ratios.

5. Atoms retain their identity in chemical reactions.5. Atoms retain their identity in chemical reactions.

MODERN ATOMIC THEORY1. Atoms are 1. Atoms are NOTNOT indivisible. They are made up of smaller indivisible. They are made up of smaller particles—protons, neutrons, and electrons.particles—protons, neutrons, and electrons.

2. Atoms can be changed from one element to another, but 2. Atoms can be changed from one element to another, but NOTNOT by by chemical reactions.chemical reactions.

3. Atoms of the same element are 3. Atoms of the same element are NOTNOT all exactly alike. They are all exactly alike. They are alike in those characteristics that determine the chemical alike in those characteristics that determine the chemical properties of an element. But atoms of the same element can and properties of an element. But atoms of the same element can and do have different masses.do have different masses.

PROTONPROTON NEUTRON NEUTRON ELECTRONELECTRONCharge:Charge: +1 +1 0 0 -1 -1Mass (amu)Mass (amu) 1 1 1 1 1/1837 1/1837

NOTENOTE: amu = atomic mass unit, a unit for expressing masses of : amu = atomic mass unit, a unit for expressing masses of atoms and subatomic particles.atoms and subatomic particles.

CHEMICAL LAWS

LAW OF CONSERVATION OF MASSLAW OF CONSERVATION OF MASSA 7.12 g sample of magnesium is heated with 1.80 g of bromine. All the bromine is used up, and 2.07 g of magnesium bromide is produced. What mass of magnesium remains unreacted?

Law of Definite ProportionsLaw of Definite ProportionsA 0.100 g sample of magnesium, when combined with oxygen, yields 0.166 g of magnesium oxide. What masses of magnesium and oxygen must be combined to make exactly 2.00 g of magnesium oxide?

Law of Multiple ProportionsLaw of Multiple ProportionsThe following data were obtained for compounds of iodine and fluorine:Compound Mass of Iodine (g) Mass of Fluorine (g) A 1.000 0.1497 B 0.500 0.2246 C 0.750 0.5614 D 1.000 1.0480 If the formula for compound A is IF, what are the formulas for compounds B, C, and D?

Workshop on CHEMICAL LAWS

LAW OF CONSERVATION OF MASSLAW OF CONSERVATION OF MASSWhen 10.00 g of marble chips, calcium carbonate, are treated with50.0 mL of hydrochloric acid (d = 1.096 g/mL), the marble chips dissolve resulting in a solution and releasing the gas carbon dioxide. The final solution weighed 60.4 g. How many liters of carbon dioxide was released if the density of the gas is 1.798 g/L?

Law of Definite ProportionsLaw of Definite ProportionsGalena, a mineral of lead and sulfur contained 2.030 g of lead in a 2.345 g sample. (a) calculate the mass of sulfur in the sample. (b) calculate the mass fraction of lead. © calculate the mass percent of lead. (d) How much reactant is needed to produce 15.000 g of product, galena?

Combined LawsCombined LawsAluminum metal reacts with bromine, a red-brown liquid with a noxious odor. The reaction is vigorous and produces aluminum bromide, a white crystalline material. A sample of 27.062 g of aluminum yields 266.705 g of aluminum bromide. How many grams of bromine will react with 15.00 g of aluminum?

may come in one of three forms:

ISOTOPIC NOTATIONISOTOPIC NOTATIONisotopes are atoms with the same number of

protons but different number of neutrons A

Z XA = mass number (the total number of protons + neutrons)Z = atomic number (the total number of protons)

X = element symbol

***The number of protons in an atom identifies that atom

*** For neutral atoms, the number of protons equals the number of electrons

Workshop on subatomic particlesDefine the following:(1) ISOTOPES:

(2) IONS:

(3) ANIONS vs. CATIONS:

(4) AMU:

(5) Complete the following table:ION # p # n # e ION # p # n # eLi+ F-

Ca2+ O2-

P-3 Sn4+

Workshop on isotopesComplete the following table:

Symbol Atomic # Charge Mass number # of proton # of neutrons # of electrons

H 0 3

Li 7 2

Al 0 27

_____ +2 58 28

_____ 78 +4 120

Atomic Mass• The atomic mass of an element represents the average mass of

all the isotopes found in nature. No element exists with only one possible isotope. Hydrogen has the smallest number of isotopes: 1H protium, 2H deuterium, 3H tritium. Its atomic mass is 1.0079 amu (atomic mass units). The atomic mass is calculated by adding the % of 1H mass found in nature to the % of 2H mass found in nature plus the % of 3H mass.

• % 1H + % 2H + % 3H = average mass (atomic mass)

• Generally the formula used is: % X + % Y + % Z… = atomic mass.

An instrument called the mass spectrometer is generally used to determine the percentages and individual masses of each isotope.

1. An element consists of 90.51% of an isotope with a mass of 19.992 amu, 0.27% of an isotope with a mass of 20.994 amu, and 9.22% of an isotope with a mass of 21.990 amu. Calculate the average atomic mass and identify the element.

2. The element silver has two naturally occurring isotopes: 109Ag and 107Ag with a mass of 106.905 amu. Silver consists of 51.82% 107Ag and has an average atomic mass of 107.868 amu. Calculate the mass of 109Ag.

3. The average atomic weight of lithium is 6.941 amu. The two naturally occurring isotopes of lithium have the following masses: 6Li, 6.01512 amu; 7Li, 7.01600 amu. Calculate the percent abundance of 6Li and 7Li in naturally occurring lithium.

AATTOOMMIICC MMAASSSS

Important Scientists and their Impact on Chemistry – you should be able to write short answer responses highlighting the important contributions of each scientist listed below (to be looked up on your own!):

1. J.J. Thomson

2. Henri Becquerel

3. Ernest Rutherford

A. Gold Foil ExperimentB. Types of radiation:

1. Alpha () radiation2. Beta () radiation3. Gamma () radiation

THE PERIODIC TABLE WORKSHOP: Contrast the organization by Mendeleev vs. Moseley

Consider the generic schematic of the periodic table shown below. Identify the chemical family or group of elements represented by each letter.

A: ________________________ E: ________________________B: ________________________ F: ________________________C: ________________________ G: _______________________D: ________________________ H: _______________________

A B

C

D E F

G

H

THE PERIODIC TABLETHE PERIODIC TABLEMetals

• Located on the left side of the periodic table

• Tends to lose electrons to form cations

• Has low ionization energies & electronegativity values

• Forms compounds with nonmetals but not other metals

• Good conduction of heat and electricity

• Lustrous & malleable solids excepts Hg which is a liquid

• Ductile

Nonmetals• Located on the right side of

the periodic table• Tends to gain electrons to

form anions• Has high ionization

energies & electronegativity values

• Forms compounds with both metals and nonmetals

• Poor conduction of heat and electricity

• Non-lustrous & brittle or gaseous

• Non-ductile

WORKSHOP on the Periodic TableBriefly describe each of the components of the periodic table:(1) Metals:

Alkali Metals:Alkaline Earth Metals:Transition Metals:Lanthanides:Actinides:

(2) Nonmetals:Halogens:Noble Gases:

(3) Metalloids: