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Chemistry 20 > Bonding Unit > Flashcards

Bonding Unit Flashcards

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0
Q

What are precious metals? Why are they precious?

A

Metals found in their pure form. Because it is rare to find non-ores in nature

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1
Q

What are ores?

A

Metals combined with nonmetals in nature

They are solids

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2
Q

What state are metals in pure form? What is the exception?

A

Solids.

Hg - Mercury

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3
Q

When nonmetals combined what states do they create?

A

Solids liquids or gases

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4
Q

What elements are never found in combined form in nature?

A

Noble gases

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5
Q

What is the octet rule?

A

The octet rule states that atoms gain, lose, or share electrons in such a way that they create a full outer energy level

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6
Q

How many electrons can be held in each energy level?

A

8e-
8e-
2e-
Nucleus

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7
Q

Do elements always follow the octet rule?

A

No, the octet rule is just a guideline

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8
Q

What are valence electrons?

A

The electrons in the outermost energy level of an atom

They are the only electrons involved in chemical bonding

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9
Q

What part of the periodic table is indicative of the number of valence electrons an element has?

A

Group number

Ignoring the 1 in front of groups above 10

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10
Q

What does period number indicate of an element?

A

The number of energy levels occupied by electrons

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11
Q

What is an electron dot diagram?

A

A model to show the structure and formation of chemical bonds
Consists of the symbol for the element with the dots representing the valence electrons

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12
Q

What is a lone pair?

What is a bonding electron?

A

A lone pair is a full orbital and is not involved in bonding ••
Bonding electrons are half full orbital •

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13
Q

What is bonding capacity?

A

The maximum number of single covalent bonds that an atom can form (Equals the number of bonding electron)

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14
Q

What is Ionic bonding?

A

Ionic bond is the electrostatic attraction between oppositely charged ions

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15
Q

How do you draw electron dot diagrams for ionic compounds?

A

Use brackets around each element
The nonmetal will have dots around it
Put the charges of each element
You may have to draw more than one of the metal and/or nonmetal to balance out the charges
The net charge on the compound must be zero

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16
Q

What is a covalent bond?

A

When two nonmetals share a pair of electrons

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17
Q

Can ions be formed during a covalent bond?

A

No

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18
Q

What are electron dot diagram used to show molecular compounds called?

A

Lewis structures

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19
Q

What is different between ionic bonds and covalent bonds?

A

Ionic bonds transfer electrons, covalent bonds share electrons to satisfy the octet rule

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20
Q

What is a double or triple bond question

A

The sharing of two or three pairs of electrons between two atoms

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21
Q

How do you draw Lewis structures?

A

Place the atom with the most bonding electrons in the centre
Arrange all atoms around it as symmetrically as possible
Share electrons to make sure that all atoms have the octet rule satisfied
Remember that hydrogen only needs to electrons to be satisfied

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22
Q

What is a structural formula (diagram) ?

A

Another way of drawing molecules

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23
Q

How do you draw the structural formula?

A

Figure out the Lewis structure

Replace all shared pairs of electrons with a line and leave off the lone pairs

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24
Q

Most metals are solid at room temperature, what does this indicate about the forces holding the atoms together?

A

Since metals are solid at room temperature, this means that there must be strong attractive forces holding the atoms of the pure metal together

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25
Q

What kind of bonds do metals not form?

What kind of bonds do metals form?

A

Covalent or ionic bonds with other metal atoms

Metallic bonding

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26
Q

What happens with the valence electrons in metallic bonding?

A

All the atoms share all of the valence electrons

The valence electrons are delocalized

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27
Q

What does delocalized mean?

A

It means they are free to move from one atom to another

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28
Q

What are metallic bonds made up of?

A

A network of positive metal ions in a sea of electrons

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29
Q

What is a metallic bond

A

The electrostatic force of attraction between the positive metal ions and the negative sea of electrons

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30
Q

What is electronegativity?

A

The relative measure of the ability of an atom to attract electrons in a chemical bond

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31
Q

Where is the electronegativity of an element found on the periodic table?

A

Below the atomic number and above the chemical symbol

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32
Q

What does higher electronegativity mean?

A

Higher electronegativity means greater attraction (affinity)

33
Q

On the periodic table what is the trend with electronegativity?

A

Electronegativity increases up a group and increases across a period

34
Q

Do noble gases have electronegativity assigned to them?

Why?

A

No. Because noble gases do not readily react with other substances

35
Q

How does electronegativity and atom size relate?

A

As you move from left to right across a period, both the electronegativity and atomic number increase, however, size of the atom decreases

36
Q

Why does size decrease across a period?

A

The size of an atom depends on the radius of energy level containing the valence electrons
In any given period, the valence electrons of each atom occupy the same energy level
As you move across the period, the atomic number increases and thus the number of protons in the nucleus increases
There is a greater amount of attraction between the nucleus and electrons when there are more protons, therefore the atom is smaller

37
Q

Why does electronegativity increase when atomic size across a period decreases?

A

It depends on two factors
•The distance between the charges - The attractive force between opposite charges decreases with the square of the distance between them
• The magnitude of the charges - The attractive force is directly proportional to the amount of charge

38
Q

Will an atom that is small and has lots of protons have a very large amount of electrostatic attraction or a very little amount?

A

Very large amount

39
Q

Why do big atoms have a small amount of electronegativity?

A

Because although they have lots of protons, they are shielded by the inner levels of electrons therefore have a small amount of attraction (electronegativity) for the electrons of another atom

40
Q

Do metals have low or high electronegativities And do they gain or lose electrons? What about nonmetals?

A

Metals have low electronegativities and lose electrons

Nonmetals have hyalite you negativities and will gain electrons

41
Q

What is an ionic bond? What is a covalent bond?

A

Ionic bonds occur between metals and nonmetals

Covalent bonds occur between nonmetal atoms

42
Q

What happens when two nonmetals have different electronegativities and share electrons?

A

The sharing is no longer equal and the elements with the higher election negativity pulls the electrons closer to itself

43
Q

What happens when two atoms have the same of electronegativity?

A

The two nuclei of the atoms will attract electrons with exactly the same strength and the electrons are shared equally between the two atoms

44
Q

What happens when the sharing between two nonmetals are no longer equal? (Regarding charges)

A

One end of the bond will have a slightly negative charge and the other end of the bond will have a slightly positive charge

45
Q

What are polar covalent bonds? What else are they called?

A

Bonds that have an equal sharing of electrons

They are also called bond dipoles

46
Q

Bond dipole arrows

A

Yes no

47
Q

What can you use to determine bond character?

A

The difference in electronegativity between two atoms

48
Q

Give a clear distinction between ionic and covalent bonding

A

Bonding is considered a continuum and there is no clear distinction between ionic and covalent bonding

49
Q

What is a crystal structure? what kind of compounds have them?

A

A 3-D array of alternating positive and negative ions. It is also called a crystal lattice. Ionic compounds have crystal structure

50
Q

Why can’t you call the attractive forces in the lattice molecules?

A

The attractive forces in the lattice are the same, each positive ion is attracted to all of the negative ions around it, and vice versa

51
Q

What does Crystal shape depend on?

A

The way the ions pack together. The relative size of the ions and the charges on the ions

52
Q

Molecular compounds, where do covalent bonds exist?

A

Between specific pairs of atoms
These compounds exist as molecule that have a given number of atoms and therefore are not necessarily written with the lowest whole number ratio

53
Q

What is the valence shell electron pair repulsion theory?

A

States that molecules adjust their shapes so that valence electrons are as far away from each other as possible

54
Q

Is electron pair repulsion always equal?

A

No, it is greatest between two lone pairs, less between a lone pair and a bonding pair, and lowest between two bonding pairs

55
Q

What is the shape of molecular compounds determined by? How many types of shapes are there?

A

Shape is determined around the central atom

Shapes can be classified into five categories

56
Q

What is the linear shape?

A

The Central atom is bonded to two other atom and has zero lone pairs, or there is only two items in the molecule

57
Q

What is the trigonal planar shape?

A

The Central atom is bonded to three other atoms and has zero lone pairs

58
Q

What is the tetrahedral shape?

A

Central atom is bonded to four other atoms and has zero lone

59
Q

What is a pyramidal shape?

A

Central atom is bonded to three other atoms and has one lone pair

60
Q

What is the bent shape?

A

Central atom is bonded to two other atoms and has either one or two lone pairs

61
Q

Memorize the shape code

A

Sure

62
Q

Can a molecule that contains polar covalent bonds the overall nonpolar?

A

The individual bonds dipoles are vectors that can be added to each other
If the bond dipoles are equal in strength and opposite direction, they cancel each other out, resulting in a nonpolar molecule
This canceling happens in symmetrical molecules

63
Q

What happens if the bond dipoles do not cancel?

A

The entire molecule will have a slightly positive and slightly negative end… Called dipoles

64
Q

What are the general rules for polarity of the molecular shapes?

A

Tetrahedral – non-polar if all atoms attached have the same pull, polar if different Adams attached
Trigonal planer - Same as tetrahedral
Pyramidal – polar as long as there is a difference in electronegativity between the atoms
Bent – polar
Linear – polar or nonpolar… Look at the electronegativity difference

65
Q

What are intramolecular forces?

A

The forces of attraction within ionic molecules

example: ionic or covalent bonding

66
Q

What are intermolecular forces?
Are they strong forces or weak forces?
What are they responsible for?

A

The forces of attraction between molecules
They are the weakest of all forces
They are responsible for state, melting point, boiling point etc.

67
Q

What are three types of intermolecular forces?

A
  1. dipole dipole forces
  2. hydrogen bonding
  3. London dispersion forces
68
Q

What are dipole dipole forces?

A

Electrostatic force of attraction between the dipoles of polar molecules
Occurs with polar molecules

69
Q

What is hydrogen bonding?

A

The attraction between a hydrogen on one molecule which is bonded to oxygen fluorine or nitrogen (HNOF)

70
Q

What are London dispersion forces?

A

The results of electrostatic attraction of induced dipoles

Occurs with all molecules

71
Q

Compare the forces strength from very low to very high

A

London dispersion and dipole dipole, hydrogen bonding, ionic bonding, covalent bonding, network covalent

72
Q

What is a network covalent?

A

Very very high force

Diamond (compressed carbon), SiC, SiO2

73
Q

What does the state of a substance depend on?

A

The strength of the attractive forces between its particles. Solids have the greatest forces of attraction, liquids have the next greatest, and gases have very few if any intermolecular attraction between the particles

74
Q

What do melting and boiling point indicate about the forces?

A

Melting and boiling points are indicators as to the strength of attraction within or between molecules

75
Q

What happens when metal melt or boil?

A

When metals melt or boil, metallic bonds must be broken

76
Q

What happens when ionic compounds melt or boil?

A

When Island compounds melts or boil, ionic bonds must be broken.

77
Q

What happens when molecular compounds melt or boil?

A

When the lecture compounds melt or boil, only intermolecular forces must be broken. (Covalent bonds do not break)

78
Q

What do delocalized electrons do to the malleability and ductility of metal?
What happens to solids that do not have delocalized electrons?

A

Delocalized electrons cause bonds to be non-directional, which allows a solid to be malleable ductile
Solids without delocalized electrons have directional bonds, which causes them to be brittle and hard

79
Q

What is electric current?
Why are metals good conductors of electricity?
Why can’t solid ionic compounds conduct electricity?

A

The directional flow of electrons or ions
Because the delocalized valence electrons are free to move
Because they have valence electrons that are held solidly in place

80
Q

Why are most molecular compounds unable to conduct electricity?
Do they conduct electricity when they melt or dissolve in water?

A

Because in most molecular compounds, valence electrons are not free to move through the molecule and therefore they are not able to conduct electricity
When molecular compounds melt or dissolve in water, they don’t form ions so they don’t carry an electric current

Chemistry 20 (5 decks)

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