Midterm Review

Burning of paper
Physical or chemical change
Chemical
Dissolving of sucrose
Physical or chemical;
physical

Which substance is an organic molecule?

H2O

NaCl

CuSO4

C2H5OH

C2H5OH

What state of matter is bromine at 65oC?

Melting Pt = -7oC

Boiling Pt = 59oC

Gas

What property of matter was the chromatography lab based on?

 

Solubility
What type of mixture is salt water?
Homogeneous

What type of mixture can be filtered?

Homogeneous or heterogeneous

Heterogeneous
A substance that cannot be broken down by any physical or chemical means is …
Element

In the reaction;

2 H2   +    O2   –>     2 H2O

How much water would form if 18 grams of H2 react with 144 grams of O2?

162 grams
What scientific law is used in the previous example?
Law of Conservation of Mass
The fact that sodium explodes in water is an example of what type of property?
Chemical
Distillation is a process that separates a mixture of liquids based on what property?
Boiling point

Round off the numbers to 3 significant figures:

57.023

 

450.00896

 

5.78  x  105

57.0

 

40.0

 

5.78 x 10

How many significant digits are in each of the numbers?

a)123.006

 

b)0.00120

 

c) 1.76  x  103

 

a)  6    [123.006]

 

b) 3   [0.00120]

 

c) 3   [1.76  x  103]

What is the answer to the correct number of significant digits?

 

12.011   +   2.5

14.5

Because the 2.5 has only 1 decimal which determines the S.F. in an addition/subtraction problem

What is the answer to the correct number of significant digits?

 

25.55   /   5.0

 

5.1 

because the 5.0 has only 2 S.F. which is the determining factor when multiplying or dividing

Convert  14.2 cm to kilometers
.000142
How many nanometers in 6 mm?
6,000,000

A car travelling at 65 mph is travelling how many Km per min?

 

(1 mile = .6 Km)

1.73 km/min

 

65mph   x  1.6 km/mi   x  1 hr/60 mins

 

What part of Dalton’s atomic theory has been amended?

Atoms are now divisible.

 

AND

 

Atoms of the same element can have different atomic masses.

What subatomic particle is a cathode ray made of?
Electrons

What particle did Rutherford aim at gold foil?

What does the particle consist of?

Alpha beam

2 protons and 2 neutrons

(a Helium nucleus)

How many protons, neutrons and electrons are in the element   P – 32?
15 protons, 15 electrons, 17 neutrons
Write the symbol for an isotope of  Si -14?
Si-15 or Si-16
According to the band of stability, what particles are in a 1:1 ratio, then a 1:1.25 ratio for atomic stability?
1 proton to 1 or 1.25 neutrons
What particle determines the identity of an element?
Number of protons
What particle determines the chemical reactivity of an element?
Electron
What are the sublevels in the 4th pricipal energy level?
s, p, d, f
What is the maximum number of electrons in the “d” sublevel?
10
What part of the Periodic Table has the “d” sublevel filling in?
Transition Metals
What is the electron configuration of Si?
1s22s22p63s23p2

Identify the element:

 

1s2 2s2 2p6 3s2 3p6 4s2 3d1

Scandium

What must be true of electrons in the same orbital?

 

They have opposite spins
What are the orbital orientation in the “p” sublevel?
px  py  pz
Why does hydrogen get placed with the alkali metals on the periodic table/
Because it has 1sas its electron configuration
What atomic property explains why the noble gases are inert?

The noble gases have a stable octet 

s2p6

What is the trend for Ionization energy across a period?
Ionization energy increases across a period.
Explain the Ionization energy trend.
Going across a period the nuclear charge increases while the electron shielding stays the same so it is harder to remove the electron.

which has the larger atomic radius

Al or Cl?

Cl

Which has the larger Ionization Energy

 

Na or Rb

Na

Because it has less electron shielding

How many electron shields are present in an atom of 

Bromine?

3

Name the compound

Na3P

Sodium phosphide

Write the formula for

dinitrogen pentaoxide.

 

Is it an ionic compound?

N2O5

No – because it is composed of 2 nonmetals.

Name the compound

 

Mg CO3

 

What type of compound is it?

magnesium carbonate

 

an ionic compound

What type of element is this

 

It has a shiny luster, is malleable and conducts electricity

 

metal

This element has an incomplete “d” sublevel,

Where is it on the periodic table?

Transition Metals

This element has the outer energy level

s2 p 6

What family is it?

Noble Gases
This element has 5 electrons in the outer 4th energy level?

 

Arsenic 

This is the only positive polyatomic ion
Ammonium   NH4

Is this electron configuration “excited”

 

1s2 2s2 2p6 3s2 3p6 4s2 4p1

 

Yes – because the last electron should fill in 

3d1

What is the frequency of a blue light with a wavelength of 450 nm?

 

3 x 108 m/sec =  wl x (450 x 10-9)

 

6.66 x 1014  Hz

Which type of electromagnetic radiation has the shortest wavelength?
Gamma
What part of the electromagnetic spectrum has the highest frequency?
Gamma
What part of the electromagnetic spectrum do we use for cooking?
Microwaves

What is amount of energy in light with a frequency of 

4.5 x 1014 Hz?

E = h Freq

(Panck’s constant)

 

(6.626 x 10-34 ) x (4.5 x 10 14)

 

2.98 x 10-19  joules

What is the difference between an extensive and intensive property?
Extensive properties deal with the amount of a substance while intensive properties are specific to the material.
Give example of an intensive property.

Density

Boiling point

Melting Point

 

Tell the number of protons, neutrons, and electrons in the following;

 

Cl – 35

Cl – 35

 

Protons 17

Neutrons – 18

Electrons – 17

Tell the number of protons, neutrons, and electrons in the following:

 

28   +3

Al

13

 

Protons – 13

Neutrons – 15

Electrons – 10

 Which is  an example of an isotope for

 

35 Br – 80

34 Se – 80

 

80 Hg – 200

 

35 Br – 81

In the nuclear reaction;

 

U-238 –>  Th 234  +  ____

 

what is the other product?

 

Alpha particle

 

4- He – 2

which particle results in the product’s atomic number increasing by 1?

 

Beta

 

    -1

e

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