Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Unit 1 Chemistry + Chromatography > Chemistry Test 3 > Flashcards

Chemistry Test 3 Flashcards

You may prefer our related Brainscape-certified flashcards:
Periodic Table flashcards Chemistry 101 flashcards AP® Chemistry flashcards Organic Chemistry 101 flashcards
1
Q

How does a covalent bond work? What kind of elements are they? between

A

Covalent bonds form between non-metal elements. It forms by the mutual sharing of valence electrons between two of such atoms.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are Lewis structures used to represent?

A

Covalent and ionic molecules and compounds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How many different types of covalent bonds are there and what are the symbols for them and what do these represent?

A

Single Bond - two atoms share 2 electrons (Pair)

Double Bond - two atoms share 4 electrons (2 pairs)

Triple Bond - two atoms share 6 electrons (3 pairs)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is a pair of electrons of a covalent atom in a molecule or compounds that is not in a double bond called?

A

Lone pair

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the small symbol for electrons?

A

e^-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are substances made of discrete covalent molecules called?

A

Covalent molecular substances

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Examples of discrete covalent molecules

A

Water (H20)
Oxygen (O2)
Carbon Dioxide (CO2)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are intramolecular forces? Are they strong or weak?

A

The intramolecular forces are the bond within these molecules, and they are strong.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are intermolecular forces? Are they strong or weak?

A

Intermolecular forces are the forces in-between molecules. These are weak and easy to break

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why do covalent molecular substances usually have low MP and BP and usually gas or liquid at room temp?

A

The forces that hold the molecules together (intermolecular forces) are weak, and can be overcome with less energy.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Why do covalent molecular substances not conduct energy?

A

There are no charged particles (electrons or ions) that move through the substance.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Why do covalent molecular substances form soft solids?

A

The forces that hold the molecules together (intermolecular forces) are weak

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Why do covalent molecular substances tend to be malleable instead of shattering?

A

Because the forces between molecules (intermolecular forces) are weak and so molecules can easily be moved around.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Why do covalent molecular substances have variable solubilities?

A

Because the solubility depends on the forces between these molecules (intermolecular forces)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Is it common for covalent molecular substances to be solids at room temperature? If so, what are these called?

A

No, it is not common, these solids are called molecular solids.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the molecular solid?

A

a 3D molecular lattice, held together by weak intermolecular forces of attraction, such as in Iodine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Properties of Molecular Solids

A
  • Low melting and Boiling Points
  • Soft and brittle - Shatter when heated
  • Cannot conduct electricity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are covalent network substances? What is their composition and give examples of such substances.

A

Covalent network substances are substances where the covalent bonds don’t form discrete molecules, but form vast networks of non-metal atoms, bonded together covalently (3D network). Examples of these substances are diamond, sand and graphite. Common elements are boron, carbon and silicon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Why are covalent network substances usually very strong?

A

The intermolecular forces in covalent network substances are effectively covalent bonds, and so inherently require a great amount of energy to disrupt.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Why covalent network substances have high MP and BP and are usually solids at room temperature.

A

The covalent bonds that hold the atoms (network) together are very strong.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Why do covalent network substances not conduct electricity?

A

There are no charged particles such as electrons or ions, free moving in the structure of the substance.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Why are covalent network substances extremely hard and brittle?

A

Covalent bonds between atoms are very strong, but an impact force disrupts the positions of atoms in the structure and cause the network to shatter.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Why are covalent network substances usually insoluble in water and most solvents?

A

No attraction between atoms in the network and water molecules. Cannot dissociate.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Allotropes/Allotropes of Carbon - Properties?

A

Both Diamond and Graphite are made up of Carbon atoms. Allotropes as such are different forms of the same element. Allotropes of Carbon have different properties as the atoms are bonded in different arrangements, which create different network structures.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Properties of Diamond - Covalent Bonding? Physical Properties?

A

All four valence electrons of the carbon’s valence shell form covalent bonds. This makes diamonds very hard, High MP and BP, and they cannot conduct electricity (no free moving charges particles such as ions or electrons)

26
Q

Graphite Properties - Covalent Bonding? Physical Properties?

A

In graphite, only 3 out of 4 valence electrons of each carbon atom are involved in covalent bonding. This makes graphite soft and slippery as layers can easily slide over each other as week forces of attraction are easily broken. Graphite conducts electricity because the 1 free electron from each carbon means that each layer has delocalized electrons which can carry charge.

27
Q

Fullerenes

A

Fullerenes are allotropes which consist of carbon atoms atoms bonded together to form an enclosed or partially closed mesh. They are covalent molecular substances.

28
Q

Buckminster Fullerenes (Bucky Balls)

A

Type of fullerene. This allotrope of carbon forms a sphere shape. Have 60 carbon atoms, each of which is bonded to three other atoms by two single bonds and one double bond.

29
Q

Carbon Nanotubes

A

They are cylindrical carbon-based covalent network substances.

30
Q

What are these fullerenes used for?

A

Medicine delivery (pharmaceutical use)

31
Q

How does ionic bonding work?

A

Transfer of electrons between metal and nonmetal atoms to reach octet configuration.

32
Q

How are ionic lattices held together?

A

Electrostatic attraction between anions and cations in the lattice

33
Q

Properties of Ionic Substances - Physical properties?

A

High Melting and Boiling points due to strong electrostatic attraction between ions

Hard and brittle (not malleable) due to strong electrostatic attraction between ions and when impacted, ions of similar charges repel each other, shattering the lattice.

They do not conduct electricity in a solid state as there are no free moving charged particles.

They have varying solubilities.

Good conductors of electricity when dissolved in water or in molten state - free moving charged particles.

34
Q

Ionic substances dissolving explanation

A

If the particles in the lattice are more attracted to each other (electrostatic attraction) than to the water molecules, it will not dissolve.

35
Q

Writing formula for ionic compounds

A

Empirical ionic formulae rules:

  • Switch charges to subscripts (unless cancels out or irrelevant; same charge like 1 and -1)
  • Transition metals have variable charges expressed as Roman numerals in brackets e.g (II)
  • Polyatomic ions also have charges and are placed in brackets if there is a subscript, these brackets can be expanded to see number of each atom needed to balance compound
36
Q

Naming ionic compounds

A

-ide suffix
no prefixes

37
Q

What is Metallic Bonding, can it conduct electricity?

A

Regular arrangement of metal atoms with electrostatic forces of attraction between nuclei of these atoms and their delocalized electron. Mobile sea of delocalized electron moves within the 3D lattice. Can conduct electricity due to free moving sea of delocalized electrons.

38
Q

How do metal atoms achieve stability in metallic bonding?

A

By offloading valence electrons to attain octet configuration. These electrons prevent newly formed positive ions from repulsing each other due to similar. charges. Metallic ions vibrate about in fixed positions in the lattice.

39
Q

Metallic Bonding strength factors?

A

Depends on the number of valences electrons donated to cloud (depends on element) and the size of the atom/ion.

40
Q

Sodium Metallic Bonding strength

A

Relatively weak as each ion only donates the one valence electron to the cloud.

41
Q

Potassium Metallic Bonding strength

A

Weaker than sodium since the resulting ion is larger and the electron cloud has a bigger volume to cover so less effective at holding the ions together.

42
Q

Mobile sea of electron + -

A

Electrons attracted to the positive end are replaced by those entering from the negative end.

43
Q

Metallic Properties - Bonding? Physical Properties?

A

Non-directional Bonding

Malleable: Can be hammered into sheets, manipulated

Ductile: Can be drawn out into rods and wires

Can be translucent at times.

44
Q

Ionic Solidity at room temperature? Reason Trends?

A

Solids at room temperature: Moderate to high temperature is needed to disrupt the lattice and allow the metal to melt.

Increases from left to right on a period.

45
Q

Ionic High Melting Point: Reasons, Factors and periodic trends?

A

Measures of how strong the cloud holds the positive ions.

Depends on:
Electron Density of the cloud
Ionic/atomic size

Melting point increases across a period. Electron cloud density increases due to the number of electrons donated per atom.

Melting Point decreases down a group, because Ionic radius increases down the group.

46
Q

What is Relative Formula Mass (Mr) + Formula?

A

Calculated from the sum of all of a molecule or compounds atoms relative atomic masses.

Mr = (no. of element x Ar of element) + same things depending on the number of elements present in the substance

47
Q

What is Percentage composition + Formula?

A

The percentage by mass of an element in a compound. Can be used to work out how pure a substance is or identify an unknown substance.

%element = ((Ar of element x number of atoms) / (Mr of compound)) x 100

48
Q

Molecular Formula vs Empirical Formula

A

The molecular formula of a compound tells you how many of each type of atom are present in one molecule. e.g. Ethane - C2H6

Empirical formula however gives the simplest whole number ratio of the type of atoms present in one molecule. e.g Ethane
- CH3. Ionic compounds always use empirical formula.

49
Q

What is the mole (SI) unit used for?

A

Describing the amount of a substance in terms of the number of particles.

50
Q

What does Avogadro’s number really represent?

A

Avogadro’s number represents the number of particles in one mole.

51
Q

How is molar mass of substances such as water, carbon dioxide, magnesium oxide and sodium hydroxide found?

A

The molar mass of these substances are found by adding together the molar masses (atomic mass) of the elements in each molecule or formula.

52
Q

Moles within Moles for 1 mole of NaOH?

A

1 mole of NaOH contains 1 mole of Na+ ions and 1 mole of OH- ions

53
Q

Moles within Moles for 1 mole of Al2(SO4)3?

A

2 moles of Aluminium ions and 3 moles of Sulphate ions

54
Q

What is Standard Pressure?

A

Standard pressure is 101.3 kPa

55
Q

Molar Volume Methods

A

STP and Non STP

56
Q

Stoichiometry

A

We can use the coefficients in a balanced equation as relative number of moles.

57
Q

How to go from number of moles to number of particles and vice versa.

A

Number of moles x Avogadro’s constant = number of particles and vice versa. divide

58
Q

Molar Volume of a Gas at STP formula

A

n(gas) = V/22.71 mol

59
Q

What is non-STP

A

Not at STP requirements

60
Q

Molar Volume of a Gas at Non STP formula

A

n(gas) = P x V/ R (universal constant) x T mol

Unit 1 Chemistry + Chromatography (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions