Class Test 1

Question 1

Relationship aming particles depends on

Answer 1

1) avg distance between particles
2) Degree of organization of particles
3) Kinds of interactions among particles

Question 2

Why do solids have high bp and mp

Answer 2

**Because of the strong packing of the particles (strong attractive forces , KE < Attractive forces)

Question 3

T/F: Solids have high desnity

Answer 3

True

Question 4

MP & BP of a solid depends on 2 things:

Answer 4

1) the strength of the attractive forces in the solid
2) Polar higher MP than non polar (Polarity)

Question 5

What is an amorphous solid + examples

Answer 5

An amorphous solid is one with** no organized structure**/orderly pattern
Example: candle wax , gel , fat tissue

Question 6

T/F: Amorphous solids have exact MPs

Answer 6

False, They gradually melt over a range of temperatures because the strength of the bonds holding the particles is not the same

Question 7

What are crystalline solids ?

Answer 7

They are solids with an orderly pattern

Question 8

Define molecular crystalline solids , give examples and state their characteristics

Answer 8

Molecular crystalline solids are made up of covalent compounds and are held together by 1)London Dispersion forces 2)Dipole-Dipole interactions(makes them easily evaporated 3)H-bonding. Characteristics: low MP , poor conductors , soft , volatile (evaporate easily). Examples: dry ice , water ice , sugar

Question 9

Define ionic crystalline solids , give examples and state their characteristics

Answer 9

Ionic crystalline solids are made up of ionic compounds (+ - charge). Held together by electrostatic forces. They’re extremely hard , brittle , have high MPs, soluble in H2O and other polar solvents. Example: chalk , NaCl, limestone, magnesium sulfate(Epsom salt).

Question 10

Covalent crystalline solids: give examples and state their characteristics

Answer 10

Are hard , brittle , insoluble in most solvents , have very high MPs. Example: diamonds and silicon.

Question 11

Define metallic crystalline solids , give examples and state their characteristics

Answer 11

Comprised of metal atoms held together by metallic bonds. Their orbitals overlap causing regions of high electron densities. Electrons can move from one atom to another because of the overlapping orbitals –> makes them great electrical conductors. Example: copper and silver. They are easily shaped.

Question 12

Why are liquids intermediate in character ?

Answer 12

Because the atoms are closely held together like solid atoms , but are disordered like gas atoms.

Question 13

Why do gases have low densities ?

Answer 13

Becaise gases have low M/V because they’re moslty empty space.

Question 14

Kinetice Molecular Theory of Gases 6 statements

Answer 14

1)atoms are in constant and random motion
2)atoms are seperated by large distances **
3)behave independently** (no attractive/repulsive forces)
4)collide with each other & walls of the container without losing energy
5)energy is transferred from one atom to another during collisions (results in random changes in direction
6)avg KE is proportional to absolute temp

Question 15

When do gases ideally behave ?

Answer 15

At low pressure and high temprature

Question 16

T/F: Gases exert pressure on their containers

Answer 16

True

Question 17

Define 1)Boyle’s Law 2)Charles Law 3)Avogadro’s Law

Answer 17

1) V&P are inversly proportional PiVi= PfVf
2) T&V are directly proportional (T in kelvin) Vi/Ti=Vf/Tf
3) Equal volumes of any gases contain the same number of moles (if measured under the sam circumstances) Vi/ni = Vf/nf

Question 18

What are: 1) the combined gas law 2) the ideal gas law

Answer 18

1) Boyle + Charles PiVi/Ti= PfVf/Tf
2) Boyle + Charles + Avogadro PV= nRT (R= 0.0821 L x atm x K^-1 x mol^-1 )

Question 19

What are intensive and extensive properties ?

Answer 19

Intensive: Independant on the quantity of substance (BP , MP, Density, Specific gravity)
Extensive: Dependent on the quanitity of the sample(Mass and Volume)

Question 20

What is a pure subtance ? Gives examples of its types

Answer 20

A pure subtance has only one component, fixed composition, and unique set of properties.
1) Element: charcoal -> carbon , (carbon is the building block of life) copper used in electrival wiring &water pipes, mercury (used in barometers and nanometers because of its high density, and used to form amalgam (Ag-Hg-Sn)used in filling teeth.
2) Compound: H20 etc.. You can resolve a compound by heating or electrolysis (if it’s a liquid)

Question 21

What are mixtures ?

Answer 21

Mixures are a combination(not chemically combined) of 2 or more substances. Each substance retains its own identity. Mixtures have** variable composition.**

Question 22

Differentiate between homogenous and hetergoneous mixtures.

Answer 22

1)Homogenous: 1-layer mixture, unifrom composition,particles are throroughly intermingled, solvents are most commonly liquid. (Alcohol+water, air, soda+water)
2)Heterogenous: 2-layer solution, non-uniform composition (salt+pepper, concrete which is mixture of various types and sizes of stones + cement)

Question 23

What is an atom ?

Answer 23

It is the basic structural and smallest unit of an element which retains the chemical properties of that element.

Question 24

Mass (amu) of e- , p+, and n

Answer 24

E: 5.486x10^-4
P: 1.007
N: 1.009

Question 25

What contains most of the atom’s mass ?

Answer 25

Nucleus(Core)

Question 26

What determines the identity of an atom ?

Answer 26

Number of protons (atomic number)

Question 27

Define an element

Answer 27

A single** simple pure substance** formed from one type of atom with similar properties, Can’t be split by chemical means into simpler form.

Question 28

What are radioisotopes ?

Answer 28

They are isotopes that emit particles and energy. Their chemical behavior is identical, but their nuclear behavior is unique.

Question 29

Give 2 examples of radioisotope usages in medicine

Answer 29

1) Radioiodine: Detects thyroid function
2) Sodium Isotope: Detects clots in the artery

Question 30

What did Bohr hypothesize ?

Answer 30

Bohr hypothesized that surrounding each atomic nucleus were certain fixed energy levels that could be occupied by the electron. This is referred to as the quantization of energy, meaning energy can have certain values .

Question 31

What happens during relaxtions ?

Answer 31

Electrons in the excited state emit energy in the form of** photons of light** until they return to the ground state.

Question 32

What is the importance of the atomic diagram and the electron structure ?

Answer 32

Is to describe arrangement of interaction between atoms of different elements.

Question 33

What is Schrodinger’s Theory ?

Answer 33

Schrodinger proposed that each of these levels is made up of one or more sublevels.

Question 34

Arrange the sublevels in order of increasing energies

Answer 34

S< P < D < F

Question 35

Give the names of the sublevels

Answer 35

S: Sharp
P: Principle
D: Diffuse
F: Fundemental

Question 36

“Electrons occupy the orbital of lowest energy first.” is which scientist’s rule ?

Answer 36

Hund

Question 37

T/F: Atoms are arranged in order of increasing atomic mass

Answer 37

F. Atomic number

Question 37

T/F: Atoms are arranged in order of increasing atomic mass

Answer 37

False. Atomic number

Question 38

T/F: The number of each period is same as the number of the main outer shell for elements of that period.

Answer 38

True

Question 39

What are trends ?

Answer 39

They’re predictable changes in a direction.

Question 40

Atomic size trend

Answer 40

Increases down a group and decreases from l to r of a period

Question 41

What is Ionization energy ? What is its trend ?

Answer 41

Is the amount of energy required to remove electron from outer shell.
Decreases down a group and increases from L to R of a period.

Question 41

What is Ionization energy ? What is its trend ?

Answer 41

Is the amount of energy required to remove electron from outer shell.
Decreases down a group and increases from L to R of a period.