Chapter 1-3 Notes

Question 1

What is Dalton’s Atomic Theory? (5 points)

Answer 1

• All matter is made up of atoms.
• Atoms of the same element are identical in size, mass and properties. Different elements have differently specialized atoms.
• Atoms cannot be divided.
• Chemical compounds are forms when atoms of different elements combine in whole-number ratios.
• Atoms can be combined, separated and rearranged.

Question 2

What differs between Dalton’s theory and modern theory? (2 points)

Answer 2

• Instead of atoms being identical in size, mass, and other properties, atoms of an element have an average mass that is unique to an element.
• Atoms cannot be subdivided, created, or destroyed in ordinary chemical reactions. But these changes can occur in nuclear reactions.

Question 3

Who discovered the electron and how?

Answer 3

JJ Thomson, using a cathode ray

Question 4

What was Thomson’s Atomic Model known as?

Answer 4

The plum pudding model. He believed that electrons were like plums embedded in a positively charged pudding.

Question 5

Who determined the mass of the electron?

Answer 5

Robert Millikan

Question 6

Who was Robert Millikan?

Answer 6

He discovered the mass of the electron.

Question 7

What were the conclusions from the study of the electron? (3 points)

Answer 7

• All elements contain identically charged electrons.
• Atoms are neutral. There must be positive particles in the atom to balance the electrons’ negative charge.
• Electrons have so little mass that other particles account for most of the mass.

Question 8

What was Rutherford’s Gold Foil Experiment?

Answer 8

Alpha particles are helium nuclei. Particles are fired at a thin sheet of gold foil. Particle hits on the detecting screen are recorded.

Question 9

What were Rutherford’s findings?

Answer 9

Conclusions from the experiment:

• Most of the particles passed right through
• Few particles were deflected

Conclusions: The nucleus is small, dense, and positively charged.

Question 10

Describe the structure of an atom.

Answer 10

• Most of the mass is in the nucleus (protons and neutrons).
• Electrons are found outside of the nuclear (the electron cloud).
• Most of the volume of the atom is empty space.

Question 11

What are quarks?

Answer 11

Quarks are fundamental particles that make up protons and neutrons in the atom’s nucleus. They are held together by gluons.

Question 12

What is a hadron?

Answer 12

A hadron is a combination of particles that have a net charge.

Question 13

What gives the identity of an element?

Answer 13

The number of protons

Question 14

What is the numerator and denominator of the fraction in front of elements?

Answer 14

The numerator is the mass number (protons and neutrons), while the denominator is the number of protons.

Question 15

How do you write an ionic formula?

Answer 15

1. Write the ions and their charges. The anion (negative) follows the cation (positive).
2. Criss-cross the charges.

Question 16

What is Avogadro’s number and why is it important?

Answer 16

6.022*10^23

This relates the number of moles in a pure substance with the number of particles in that sample. (Translation: One mole of whatever will always be Avogadro’s number.)

Question 17

What determines if something is an acid?

Answer 17

The presence of hydrogen

Question 18

How do you name an acid NOT containing oxygen?

Answer 18

1. The H+ cation becomes the prefix “hydro-.”
2. The suffix “-ic” gets added to the root name of the anion.

Example: HBr, hydrobromic acid

Question 19

How do you name an oxyacid?

Answer 19

If the name of the polyatomic anion ended with “-ate,” it will be changed to “-ic.” Change it to “-ous” if it was “-ite” originally.

H2SO4, sulfuric acid

Question 20

What is the purpose of mass spectrometry?

Answer 20

Produces spectra of masses from the molecules in a sample of material and fragments of the molecules

Question 21

What are the uses for mass spectrometry? (5 uses)

Answer 21

This can be used to determine elemental compositions of a sample, masses of particles and molecules, chemical structures of molecules, the identity of unknown compounds (matching to known spectra), and isotopic composition of elements in a molecule.

Question 22

What are the stages of mass spectrometry? (3 stages)

Answer 22

1. The ionizer converts some of the sample into ions.
2. Mass analyzers separate the ions according to their mass-to-charge ratio.
3. The detector records either the charge induced or the current produced when an ion passes by or hits a surface.

Question 23

What is a digit that is estimated called?

Answer 23

Uncertain. A measurement always has some degree of uncertainty, because measurements are performed using instruments that don’t have an infinite number of decimal places.

Question 24

What the difference between accuracy and precision?

Answer 24

Accuracy if the agreement of a particular value with the true value. Precision refers to the degree of agreement among several measurements made in the same manner.

Question 25

What’s the difference between a random error and a systematic error?

Answer 25

A random error is a measurement that had an equal probability of being high or low from the accurate result. A systematic error occurs in the same direction each time (high or low), usually a result of a flaw in technique. (This results in precise, but not accurate measurements.)

Question 26

What is the rule of significant figures when multiplying and dividing?

Answer 26

Use the least amount of significant figures as indicated by one of the numbers being multiplied or divided.

Question 27

What is the rule of significant figures when adding and subtracting?

Answer 27

Use the least amount of decimal places as indicated by one of the numbers being multiplied or divided.