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Chem 20 > Unit 1: Bonding > Flashcards

Unit 1: Bonding Flashcards

1
Q

What are Lewis dot diagrams?

A

They are representations of how atoms could achieve stable electron arrangements by sharing or transferring electrons.

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2
Q

what are valence electrons?

What are they used for?

A

electrons in the highest energy level (outermost shell)

They are the only electrons used in a chemical reaction.

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3
Q

What is an orbital?

What do you need to do to get a full orbital?

A

A region where two electrons may exist.

each orbital can hold two electrons and there are entire four or one orbitals depending on an energy level.

In order to get a full orbital, all other orbitals must have one electron.

for example: if you were trying to create a diagram of aluminum you cannot get a full orbital because you would get an empty orbital.

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4
Q

What is a chemical bond?

A

electrostatic attraction between 2 particles (ions, atoms, molecules)

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5
Q

what are ionic bonds?

A

The attraction between negative and positive ions, resulting in the transfer of valence electrons.

(two elements give and take electrons to fill valence shell)

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6
Q

What are covalent bonds?

A

The simultaneous attraction of nuclei of two atoms to share electrons
(sharing electrons to fill valence shell)

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7
Q

what are single, double, and triple covalent bonds?

A

It is the different amounts of electrons shared in covalent bonds (shown through the connected lines)

single = two electrons shared

double = four electrons are shared

Triple = six electrons are shared

(all shared electrons are used with the remaining electrons to complete the shell of the non-metals)

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8
Q

What is stereochemestry?

A

Study of 3D spatial configuration of molecules and how it affects reactions.

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9
Q

What is the VSEPR Theory?

A

It stands for Valence Shell Electron Pair Repulsion.

The number of electrons surrounding the central atom can predict the stereochemistry of a molecule

Key concept: all pairs of valence electrons repel each other and try to get as far away from each other as possible.

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10
Q

How to draw the different types of diagrams for molecules?

A

Review NOTES!!!

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11
Q

What happens when two electrons get closer to each other?

A

They repel.

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12
Q

What are the three different lines used to represent a 3-D shape of a molecule?

A

Solid line = directly plane

Wedged line = front Z plane

Dashed line = Back Z plane

(Z is front and back, X is left and right)

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13
Q

What does A, X, and E mean in a general formula

A

A = number of peripheral atoms (almost always one)

X = number of peripheral atoms

E = lone pairs

(the formula made with these variables helps you figure the shape of the atom)

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14
Q

What is the geometry of the formula AX2

A

Triatomic linear - a straight line

Only uses straight lines

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15
Q

Why can boron bond with six? And beryllium bond with four?

A

Because their electrons are super close to the nucleus they can bond with fewer atoms

(Only them though)

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16
Q

What is AX3?

A

Trigonal planar - Y shape

Only straight lines

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17
Q

What is AX4?

A

Tetrahedral - a Birds-foot shape

has one dashed, one wedged, and two straight lines

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18
Q

What is AX3E?

A

Trigonal Pyramidal - Pyrimid

(One dashed, one dotted, and one straight).

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19
Q

What is AX2E2?

A

V- Shaped, Bent, Angular, - Tipi

Two straight lines

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20
Q

What is AXE3?

A

Diatonic linear - Pair

one straight line

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21
Q

What is Electronegativity?

How can you have higher electronegativity?

A

The relative ability of an atom to attract bonding pair electrons in valence orbital

More electrons in valence = higher electronegativity

Less energy levels = higher electronegativity

This means nonmetals have higher electronegativity

(Nobel gases do not have electronegativity because of their stability)

22
Q

What are the characteristics of covalent bonding?

How does the bonds work?

A

If both atom’s electronegativity is high, the bonding pair is shared

This is then usually two non-metals

The simultaneous attraction of nuclei for a shared pair of bonding electrons

23
Q

What is metallic bonding?

What are its characteristics?

A

If both electronegativities are low atoms share electrons as they move freely through the compound (this is why metals are conductive)

creates an attractive force around metal in all directions

Atoms in solid metals may move around each other without moving apart. This creates its malleability and ductility.

(Not ionic compounds because this is TWO metals)

24
Q

What does the difference of EN give you?

And their difference numbers for each

A

Larger than 1.7 = Ionic

  1. 4 - 1.7 = polar covalent
  2. 4 - 0 = nonpolar covalent

0 or 0.1 between metals = metallic

25
Q

What molecule can be dissolved into polar and non-polar solvents?

A

Polar compounds are soluble in polar solvents

And non-polar compounds are soluble in non-polar solvents

26
Q

What happens when you mix polar and non-polar liquids

A

It results in creating layers of liquid where the least dense liquid is on top.

27
Q

What are miscible liquids?

A

They mix well in general together.

Both polar or non-polar

28
Q

What are Immiscible liquids?

A

Do not mix and form layers.

Polar and non-polar

29
Q

What is the smallest unit in a ionic compound?

A

A formula unit

30
Q

What is intramolecular bonds?

A

Attraction within the molecule.

31
Q

What is intermolecular bonds?

A

Attraction and repulsion between molecules.

32
Q

What are the properties of intermolecular bonds?

What Increases Intermolecular bonds force?

A

Only occurs in substances that have movement bonds. (non-metals)

Weaker than ionic, covalent, and metallic bonds

The greater complexity of the molecule the strong the intermolecular bonds.

This results in a higher melting and boiling point.

33
Q

How many KJ/mol does it take to change the sate of water from liquid to gas?

A

41KJ/MOL

34
Q

how much KJ/MOL does it take to break the covalent bonds of water

A

286KJ/MOL

35
Q

What are IMF’s

A

Intermolecular forces.

36
Q

What is IMF’s?

A

intermolecular forces.

It is the attraction and repulsion force of MOLECULES.

37
Q

What is London force?

A

Present in all molecules

The momentary dipole in and around the molecules causes attraction.

(uneven distribution of electrons around a molecule results in a temporary charge difference)

The strengths are correlated to the number of electrons.

More electrons = higher boiling point

38
Q

What is dipole dipole force?

A

The attraction and repulsion of positive and negative ends of a POLAR MOLECULE

(Think of it as magnets)

39
Q

What are isoelectronic molecules?

What approximate effect does it have on their London forces?

A

Molecules with the same number of electrons have approximately the same strengths as London forces

However, If one molecule is way larger then it is a greater London force.

40
Q

What is Hydrogen bonding?

How does it work?

Are they stronger than a covalent bond?

A

When hydrogen atoms are BONDED with Fluorine, Nitrogen or Oxygen, the electron is pulled far away from the nucleus.

This results in hydrogen having an unshielded nucleus, made up of one proton.

Even though hydrogen bonds are strong intermolecular forces, they are still not as strong as a covalent bonds.

41
Q

Why is water less dense and expands when frozen?

A

The H bonds hold water molecules in a hexagonal lattice which creates a large-ish open space in the middle.

This allows water to be less dense and expand when frozen.

42
Q

What can IMF’s explain?

A

Melting and boiling point.

Solubility

Surface tension

Volatility = evaporation (if IMF is weak evaporation will occur readily)

Capillary action

Shape of meniscus

43
Q

Is intramolecular forces stronger than intermolecular forces?

A

Yes

44
Q

What are the characteristics of solids?

A

They have a definite shape and volume

Do not compress or flow

They vary in melting point, hardness and conductivity

45
Q

What are the classes of solids?

A

Ionic, metallic, molecular, and covalent network

46
Q

What is are the properties of ionic crystals?

A

Made from cations and anions through ionic bonds

They are hard, brittle, high melting point, when in aqueous form conductive.

47
Q

What types of properties do metallic crystals have?

What are metallic crystals made from?

A

Made from cations and electrons through metallic force.

They are soft to hard, ductile, malleable, lustrous, and conduct in solid or liquid form. They have a slightly low melting point.

48
Q

What are the characteristics of molecular crystals?

A

Made from molecules using LDF, DDF, and HB

They are soft, have a low melting point, and does not conduct electricity in all forms.

49
Q

What do you do if both molecules are isoelectric and have the same forces, and you need to find their boiling point?

A

You pick the biggest molecule (the one with the most atoms)

50
Q

From lowest to highest rank the boiling/melting point of solids.

A

Molecular, metallic, ionic, covalent network.

51
Q

Three types of covalent networks that you need to memorize?

A

C (in diamond form) SiO2 (sand/silica) SiC (silicon carbide) C (in graphite form)

52
Q

Can you fulfil the octet rule with an odd pair of electrons?

A

No. The number of valence electrons must be even to satisfy the octet rule.

Chem 20 (6 decks)

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