Chem chap 1

Question 1

Put these models of the atom in order, from earliest to latest, and identify the scientist who is responsible.

Planetary, Plum pudding, Billiard ball, Beehive

Answer 1

Billiard Ball, Plum Pudding, Beehive, Planetary

Question 2

What experiments did Dalton preform? What contributions did Dalton make to the atomic theory?

Answer 2

Dalton came up with theories such as Dalton’s Atomic Theory along with creating the Billiard Ball Model.

Question 3

What experiments did Thomson preform? What contributions did Thomson make to the atomic theory?

Answer 3

Thomson discovered the electron VIA cathode ray tubes. This contriuted to the atomic theory by discovering the negatively-charged particles in atoms. Made the plum-pudding model.

Question 4

What experiments did Rutherford preform? What contributions did Rutherford make to the atomic theory?

Answer 4

Rutherford discovered the nucleus of the atom when he preformed the gold foil experiment. After preforming the experiment, Rutherford infered that there was a positive charge in the atom.

Question 5

What experiments did Bohr preform? What contributions did Bohr make to the atomic theory?

Answer 5

Bohr suggested that electrons were in fixed orbits around the nucleus, and that each orbit had a different energy level and was a different distance away from the nucleus. He did this by observing the emission spectrum of hydrogen.

Question 6

What is the definition of an ion?

Answer 6

An atom with a charge.

Question 7

What is the definition of a cation?

Answer 7

A postivley charged ion.

Question 8

What is the definiton of an anion?

Answer 8

A negatively charged ion.

Question 9

What is the definiton of multi-valent?

Answer 9

Atoms with more than on possible charged.

Question 10

Why do atoms form ions?

Answer 10

To create stable elements.

Question 11

How do atoms form ions?

Answer 11

By giving away or taking electrons.

Question 12

What is the definiton of an isotope?

Answer 12

They are variations in the atoms mass. (C-12, C-13, C-14)

Question 13

What is the definiton of a radioisotope?

Answer 13

An unstable form of a chemical element that releases radiation as it breaks down and becomes more stable.

Question 14

What is the definiton of relative atomic mass?

Answer 14

1 atomic mass unit = 1/12 the mass of C-12
(1.66 * 10^-27)

Question 15

The atomic mass of chlorine is 35.45 u. Is it possible for any single atom of chlorine to have a mass number of exactly 35.45 u? Explain.

Answer 15

No, it has to be a whole number.

Question 16

Naturally occurring chlorine consists primarily of two isotopes: Cl-35 and Cl-37. Determine the number of protons, neutrons and electrons for an atom of each isotope.

Answer 16

Cl-35: protons = 17
electrons = 17
neutrons = 35 - 17
= 18
Cl-37: protons = 17
electrons = 17
neutrons = 37 - 17
= 20
(the protons and electrons stay the same because we are using the numer that shows up on the periodic table)

Question 17

Potassium naturally consists of 93.10% K-39 and 6.90% K-41. Calculate the atomic mass for potassium.

Answer 17

(0.9310 * 39) + (0.0690 * 41)
= 39.138

Question 18

What are the similarities between Mendeleev’s Periodic Law and Modern Periodic Law?

Answer 18

• They are both organized in rows and columns.
• Both incorporate mass and prooperities.

Question 19

What are the differences between Mendeleev’s Periodic Law and Modern Periodic Law?

Answer 19

• Modern Periodic Law is organized by incerasing atomic number while Mendeleev’s Periodic Law was organized by increasing atomic mass.

Question 20

What is the order of elements?

Answer 20

Elements are arranged by increasing atomic number.

Question 21

What are the four “famous” groups on the periodic table.

Answer 21

1. Alkali Metals (Group 1)
2. Alkaline Earth Metals (Group 2)
3. Halogens (Group 17)
4. Noble Gases (Group 18)

Question 22

What are the properties of the four “famous” groups?

Answer 22

Alkali: Most reactive metals
Alkaline Earth: Second most reactive metals
Halogens: most reactive non-metals
Noble Gases: Unreactive

Question 23

What are the three types of elements ad where are they on the periodic table?

Answer 23

• Metals (on the left)
• Non-metals (on the right)
• Metalloids (in the middle of the other two)

Question 24

How many periods are there on the periodic table? How many groups are there on the periodic table?

Answer 24

• 7 periods
• 7 representative groups (1, 2, 13 - 18)

Question 25

What is net attractive force (aka effective nuclear charge, Zeff)?

Answer 25

Effective Nuclear Charge (Zeff) = Z - S

Z = # of protons
S (sheilding effect) = # of core electrons

Question 26

What is the role of nuclear charge (number of protons) and shielding electrons?

Answer 26

The shielding effect explains why valence-shell electrons are more easily removed from the atom. The more protons there are, the igher the attraction is between the sheilding electrons and the protons.

Question 27

What is the definiton of atomic radius?

Answer 27

The distance from the nucleus to the valence eectrons. Usually expressed in picometres (pm).

Question 28

What is the definiton of ionization energy?

Answer 28

The energy required to remove an electron from an atom or ion. Expressed in kijoules/mole (kJ/mol).

Question 29

What is the definiton of electron affinity?

Answer 29

The energy change that occurs when an atom GAINS an electron. The smaller the atom, the larger the EA; the “pull” of the nucleus makes it easier to gain the electrons.

Question 30

IE is greatest when it is ______ to ______ an electron. This is the case with _______ atoms.

Answer 30

harder, remove, smaller

Question 31

EA is greatest when it is ______ to ___ an electron. This is also the case with _______ atoms.

Answer 31

easier, add, smaller

Question 32

Explain the differences in atomic and ionic radii.

Answer 32

The primary distinction between atomic and ionic radius is that atomic radius refers to a neutral atom’s radius, whereas ionic radius refers to an electrically charged atom’s radius.

Question 33

Explain the differences for an ion and its neutral atom.

Answer 33

By definition, an ion is an electrically charged particle produced by either removing electrons from a neutral atom to give a positive ion or adding electrons to a neutral atom to give a negative ion.