ATOMIC THEORY

Question 1

a. 4.3 x 10E4 + 2.9 x 10E5 =
b. 6.8 x 10E-6 + 5.2 x 10E-5 =
c. (5.7 x 10E8) (3.2 x 10E-6) =
d. (7.9 x 10E-6) / (4.3 x 10E7) =

Answer 1

make exponent same and then add the column, round sig figs
4.6x10E6
5.9x10E-5
1.8x10E3
1.8x10E-13

Question 2

What is the mass of a piece of metal that has a density of 7.50 g/cm3 and a volume of 25.89 cm3?

Answer 2

D=M/V 194 g round to sig figs of least accurate

Question 3

Dalton, what did he do regarding atomic theory? What were his Postulates (in order)?

Answer 3

Dalton gave 4 postulates
all matter is composed of atoms
atoms of the same element are identical
Different elements have different atoms
atoms combine in simple whole-number ratios to form compounds

Question 4

J.J. Thompson, what did he do regarding atomic theory?

Answer 4

discovered the electron

found charge/mass ratio e-/mass ratio = -1.76x10E8 c/g

Question 5

Rutherford, what did he do regarding atomic theory?

Answer 5

found most of the atom is empty space with electrons scattered throughout

nearly all mass and positive charge are located in the nucleus

Question 6

Milikan, what did he do regarding atomic theory?

Answer 6

found the charge of an electron (-1.6x10E-19) and helped JJ Thompson calculate the mass of an electron

Question 7

Daltons Postulates in order.

Answer 7

all matter is composed of atoms
atoms of the same element are identical
Different elements have different atoms
atoms combine in simple whole-number ratios to form compounds

Question 8

What is the average atomic mass of an element with the following isotopes?

Mass % Composition
23.9 10.0
24.3 20.0
23.3 60.0
23.1 10.0

Answer 8

23.6 amu add all and round to least accurate column round each equation to sig figs before adding columns

Question 9

What is an Atom?

Answer 9

The smallest unit
 Electrically neutral
 p+ = e- = Atomic# (Z)
 The number of protons in the nucleus is given by the Atomic Number (Z)
 The mass of an atom is found by adding the number of protons and the number of neutrons (n0)
 A = atomic MassA = Z + n0 Z = A - n0 n0 = A - Z

Question 10

What is an Ion?

Answer 10

An atom that has lost or gained electrons
 Is NOT electrically neutral
 The charge can be positive or negative
 The charge must be shown as a part of the symbol of the ion
 It CAN NOT be called an atom

Question 11

Explain the difference between an atom, an Ion, and an Isotope of lithium.

Answer 11

An atom of lithium is electrically neutral and has the same protons and electrons

An ion of lithium has a +1 charge as lithium will lose 1 electron and become Li+

An isotope of Lithium is electrically neutral but has a different number of neutrons

Question 12

Give the electron configuration for Magnesium (Mg). Use kernel method

Answer 12

Mg: [Ne]3s2

Question 13

Give the electron configuration of Potassium (K). Use longhand method.

Answer 13

K:1s22s22p63s23p64s1

Question 14

What is an Isotope?

Answer 14

Most elements are composed of a group of atoms with the ___same number of protons but with different numbers of neutrons___

 Together the group is referred to as the Isotopes of the element
 Isotopes will have different masses due to the difference in neutrons
 1p+ = 1.7x10 -27 g = 1 amu (Atomic Mass Unit)
 1 n0 = 1.7x10 -27 g = 1 amu
 The periodic table only reports one mass value per element. This is the element’s Average Atomic Mass(m)

Question 15

Give the names and symbols for two metallic ions and two non-metallic ions that have the same electron configuration as neon.

Answer 15

Neon configuration:1s22s22p6

elements with the same config:

Al+3,Mg+2,Na+1 -> metallic ions
F-,O-2,N-3 -> non metallic ions

Question 16

Give the electron configuration and the dot diagram for the following elements:
Z = 5
Z = 9
Z = 15
Z = 19

Answer 16

REMEMBER 2 on right fill 1st lewis dot diagram

Z=5, B: 1s22s22p1 B (3 valence e-)
Z=9, F: 1s22s22p5 F (7 valence e-)
Z=15, P: 1s22s22p63s23p3 P (5 valence e-)
Z=19, K:1s22s22p63s23p64s1 K (1 valence e-)

Question 17

Describe the chemical activity of the Alkali Metals. Explain why changes in activity occur as the atomic number increases.

Answer 17

-Chemical activity increases
-Increasing size
-Sheilding
-Losing e-

Question 18

Describe the chemical activity of the Halogens. Explain why changes in activity occur as the atomic number increases.

Answer 18

-Chemical activity decreases
-Increasing size
-Shielding
-Gaining e-

Question 19

Describe the chemical activity of the Noble gases. Explain why changes in activity occur as the atomic number increases.

Answer 19

FULL outer shells. little/no activity.

Question 20

If a substance has a melting point of 40 °C and a boiling point of
140 °C, will it be a solid, liquid, or gas at:
a. 50 °C
b. 150 °C
c. 25 °C

Answer 20

a. liquid, b. gas, c. solid

Question 21

Write a balanced equation for the reaction between lithium and water.

Answer 21

Li + H20 -> Li+ + OH- + H2 = 2Li + 2H2O -> 2Li+ +2OH- +H2

Question 22

Write the balanced equation for the reaction between the Alkali Metal and the Halogen atom in the fourth period.

Answer 22

K + Br2 -> KBr = 2K + BR2 -> 2KBr

Question 23

Why do Noble Gases have very low boiling points?

Answer 23

-weak forces of cohesion
-complete main energy levels

Question 24

Why do the Alkali Metals have a higher boiling point than the Halogens?

Answer 24

-Stronger forces of cohesion
-Incomplete main energy levels

Question 25

Name the members of the Alkalai metals. Describe four general trends in properties that occur as the atomic number increases.

Answer 25

Li,Na,K,RB,Cs,Fr

-Atoms increase in size
-Outer e- gets pulled further away from the nucleus
-Inner e- shield the outer valence e- from the (+) nucleus
-Chemical activity increases as Z increases

Question 26

Name the members of the Halogens. Describe four general trends inproperties that occur as the atomic number increases.

Answer 26

F,Cl,Br,I,At
-Atoms increase in size
-Outer e- gets pulled further away from the nucleus

-Inner e- shield the outer valence e- from the (+) nucleus
-Chemical activity decreases as Z increases

Question 27

Name the members of the Noble gases. Describe general trends in properties that occur as the atomic number increases.

Answer 27

He,Ne,Ar,Kr,Xe,Rn

-Chemically inactive due to full outer valence shell
-Forces of cohesion are weak between atoms

Question 28

The region of space around a nucleus in which an electron is most likely to be found is called an _____

Answer 28

Orbital

Question 29

An atom in its lowest energy state is called a ______

Answer 29

Ground state

Question 30

When the atom absorbs heat energy it exists for a short time in an ________
It will then ____ _______ in the form of _____ over a period of time

Answer 30

Excited state, emit, energy, light

Question 31

Max electrons and orbital equations

Answer 31

2n2 and n2

Question 32

Sublevel, name them lowest to greatest

Answer 32

A level that is below another level

S p d f

Question 33

What is the principal quantum number?

Answer 33

The principal number (n) tells us which period we are in in the periodic table. Tells us which energy level we are in/ describes the energy level

Question 34

What are diatomic elements? Which elements are diatomic?

Answer 34

Elements that can only exist by themselves when bonded. Ex. Oxygen must be written as O2.

H, O, F, Br, I, N, Cl

Question 35

What is a continuous line spectrum?

Answer 35

When white light is passed through a prism a continuous line spectrum of wavelengths of light and patterns of colours are observed

Question 36

What is a line spectrum?

Answer 36

When heat is applied to an atom and the light from the heated atom is passed through a prism, a line spectrum is observed.

Each element has a unique line spectrum

Question 37

What is quantum mechanics?

Answer 37

Studies how particles behave on the smallest scale. Ex. Atoms and subatomic particles

Quantum mechanics makes it possible for us to calculate where an electron might be in orbit.

Quantum mechanics describes the behaviour of electrons in quantized energy changes.

Proves there is no specific path electrons follow as Bohr believed

Question 38

How many electrons in an orbital?

Answer 38

2