For Graded Assessments, You Will Need to Be Familiar with the Following Terms

Chemistry I Chapter 3 Outline

ATOMS: THE BUILDING BLOCKS OF MATTER

For graded assessments, you will need to be familiar with the following terms:

Law of conservation of mass, law of definite proportions, law of multiple proportions, atom, nuclear forces, atomic number, isotope, mass number, nuclide, atomic mass unit (amu), average atomic mass, mole, Avogadro’s number, molar mass.

I. THE ATOM: FROM PHILOSOPHICAL IDEA TO SCIENTIFIC THEORY

A. Foundations of Atomic Theory: Be familiar with names that are attributed to theorizing about the smallest, indivisible part of matter (the atom); names from ancient Greece as early as 400b.c. such as Democritus and Aristotle. (pg. 67)

i. Which of the two above philosophers first described the atom as “indivisible”?

______

ii. Which of the two above mentioned philosophers did not believe in the atom but instead believed that all matter was continuous?

______

(STANDARD: CLE 3221.1.1)

B. Dalton’s Atomic Theory: Be familiar with Dalton’s 5 statements that theorized the characteristics of all atoms. (pg. 68)

i. All matter is composed of

______called atoms.

ii. Atoms of a given element are identical in ______,

______, and other ______; atoms of different

elements differ in ______, ______, and

______.

iii. Atoms cannot be ______, ______, or

______.

Iv. Atoms of different elements combine in simple

______to form

compounds.

v. In chemical reactions, atoms are ______,

______, or ______.

**NOTE: the purpose of this exercise is to practice associating these ideas with the historical scientist John Dalton. There is, in fact, a unit of measurement named after him in the sub discipline, biochemistry. Dalton’s atomic theory will come up many times throughout your academic career in the sciences and as such, it is also a standard that his theory work is familiar.

vi. According to Dalton’s theory, the law of conservation of mass

is explained in that chemical reactions involve merely the

combination, separation, or rearrangement of atoms and that during

these processes atoms are not subdivided, created, or destroyed.

Refer to pg. 69, figure 2. Which example illustrates this law?

______

Which of the two illustrates the law of definite proportions?

______

Define the law of definite proportions.

______

______

______

______

______.

C. Modern Atomic Theory: Understand that although these historical scientific pioneers contributed greatly to what we understand about science today, their ideas, particularly Dalton’s, have been modified according to more contemporary scientific data.

i. One important concept that remains unchanged is that

ii. Another concept that remains unchanged is that

______

______

______

(STANDARD CLE 3221.1.1 & CLE 3221.3.4)

II. THE STRUCTORE OF THE ATOM(pg. 72 – 76)

1. Electron Discovery: What are the two regions that all atoms have?

______.

i. The nucleus consists of the subatomic particles ______

and ______.

ii. ______are located outside the nucleus, are in constant orbital motion about the nucleus, and are involved in forming chemical bonds.

iii. Proton, neutrons and electrons are called

______.

iv. What is a cathode ray composed of?

______

______

v. Ernest Rutherford used what to help substantiate the composition of an

atom?______

vi. According to Rutherford et. al., the nucleus of an atom is

incredibly ______; this conclusion was based on the

fact that the alpha particles that bombarded the gold foil

______.

vii. Please review Rutherford et. al., experiment illustrated on pg. 74, figure 6. Be able to explain how this group of researchers were able to theorize on the structure of an atom and how their theories contribute to contemporary science and our understanding of the atomic structure – the fact that an atom is composed of an incredibly dense nucleus composed of protons and neutrons with a ‘cloud’ of electrons in constant orbital motion about this positively charged nucleus.

B. Composition of the Atomic Nucleus: The proton’s positive charge is equal in magnitude to the negative charge of an electron. Atoms are electrically neutral because they contain equal numbers of protons and

electrons. A neutron is ______.

i. In terms of mass, list the greatest to the smallest of the

subatomic particles.______

ii. The number of protons determines that atom’s ______.

iii. Define nuclear forces. ______

______

______

______.

C. The Sizes of Atoms: Because atomic radii are so small, they are

expressed using what unit? ______.

Express the conversion factor for 1pm to the meter. ______

______.

(STANDARDS CLE 3221.1.1 & CLE 3221.Inq.2 – 6)

III. COUNTING ATOMS (pg. 77 – 87)

A. Atomic Number: Define the atomic number as it appears on a periodic

table of elements.

______

______.

B. Isotopes: are atoms of the same ______that have different

______. They have a different number of ______than

______; this is why they have a different mass from a ground state elemental atom.

C. Mass Number: the mass number of an element is the total number of

protons and neutrons that make up the nucleus of an isotope or atom.

1. Review table 2 on page 78 for an example of the difference between the varying isotopes of the hydrogen atom.

D. Designating Isotopes: Review this section and understand how isotopes are expressed. If you have questions, please let me know. For example, Uranium – 235 has a mass number of 235 which is the protons + neutrons but Uranium only has 92 protons, therefore it will have 143 neutrons. You will need to refer to your periodic table to confirm this.

E. Relative Atomic Masses: Know that one atomic mass unit, or 1 amu, is 1/12 of the mass of a carbon-12 atom.

i. Although isotopes have different masses, they do not differ

significantly in their ______. (pg. 81)

F. Average Atomic Masses of Elements: Define average atomic mass.

______

______

i. Understand relative abundance of elemental species as indicated on pages 80 – 82.

G. Relating Mass to Numbers of Atoms: Define the mole. ______

______

______.

H. What is Avogadro’s Number? ______

______

______

I. Molar mass is defined as the mass of one mole of pure substance.

J. Practice the sample problems on pages 84 – 87. You will need to know how to convert grams to moles, moles to grams, moles to atoms, atoms to moles and etc….

(STANDARD CLE.3221.MATH.2)