Chemical Bonding Flashcards

1
Q

Chemical Bond

A

an attraction between atoms for electrons

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2
Q

A chemical bond involves:

A
  • attraction between nuclei for electrons
  • electrons may be lost, gained, or shared when forming a bond
  • the # of electrons in a chemical bond is such that each atom fills its valence shell
  • 8 electrons fill the valence shell expect H and He only need 2
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3
Q

When a bond is broken..

A

heat energy is absorbed and it’s an endothermic process

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4
Q

When a bond is formed…

A

heat energy is released and it’s an exothermic process

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5
Q

When energy is on left.. H2 + I2 + 53 KJ -> HI

A

more energy is absorbed to break bonds so it’s endothermic

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6
Q

When energy is on right.. H2 + I2 -> H20 + 483.6 KJ

A

more energy is released in forming bonds so its exothermic

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7
Q

Potential Energy

A

amount of energy stored within the bonds (distance between the atoms involved in the bond)

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8
Q

When more energy is used to break bonds reaction is (endo) the potential energy

A

increases

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9
Q

When more energy is used to form bonds reaction is (exo) the potential energy

A

decreases

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10
Q

with endothermic the…

A
  • potential energy increases
  • breaking bonds
  • less stable process
  • easy to decompose
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11
Q

with exothermic the…

A
  • potential energy decreases
  • forming bonds
  • more stable process
  • hard to decompose
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12
Q

Ionic Bonds

A

form when metals transfer valence electrons to non-metals

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13
Q

Ionic bonds are formed from the attraction between

A

positive and negative ions

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14
Q

Ionic Substances are called

A

ionic compounds not molecules because molecules have neutral particles

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15
Q

Ionic Bond Characteristics

A
  • ionic bonds are very strong
  • ions are held in a fixed position in a “crystal lattice structure.”
  • ionic compounds are solids at room temp
  • they have high melting points and high boiling points
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16
Q

Ionic Compounds are

A

poor conductors as solids, good conductors when melted, good conductors when dissolved in water because ions are free to carry a current; soluble in polar solvents (ex. H2O)

17
Q

Ionic bonds form when

A

elements with large differences in electronegativity combine (difference 1.7 or greater ) - the stronger the ionic bond the greater the difference in EN

18
Q

ionic bonds have what type of diagram?

A

simple lewis dot diagram so like Br with it’s number of valency electrons or A metal with it;s ions and then a non metal with brackets.

19
Q

Covalent Bonds

A

involve the sharing of electrons between 2 non- metals - no ions are involved only molecules

20
Q

Properties of Covalent Bonds

A

A.K.A molecular substances (neutral)
most are poor conductors in all three phases of matter - including water (ex. Sugar) - low melting and boiling points
weak forced hold molecules together

21
Q

Non Polar Covalent Bonds

A

involve equal sharing of electrons (electrons spend same amount of time in the valence shell of both atoms )
form between 2 identical non-metals atoms - diatomics

22
Q

Polarity

A

refers to charge ; so non polar refers to no difference in charge - the electronegativity difference is always 0

23
Q

Allotropes

A

are different forms of an element - different physical properties due to different arrangement of atoms with different structure (diamond, graphite + oxygen and ozone)

24
Q

Polar covalent bonds

A

a bond in which atoms of 2 different non-metals share electrons unequally - electronegativity difference is between 0 and 1.7

25
Q

Ionic and Covalent bonds

A

compounds that are composed of both ionic and covalent bonds contain polyatomic ions

26
Q

Co-ordinate Covalent Bonds

A

AKA - free loader bonds: one atom supplies both electrons (lone pair) to be shared

27
Q

Network Bonds

A

consists of special covalently bonded atoms in a network; strong bonds; no separate particles; ultra high melting points; poor conductors; very hard substances

28
Q

what are the 4 examples of network bonds?

A

diamond, graphite, SiO2, and SiC

29
Q

Metallic Bonds

A

bonds that hold metal atoms together; very strong bonds, + nuclei in a ‘sea of mobile electrons” - free moving electrons give metals luster and conductivity - metals are good conductors in all 3 phases of matter

30
Q

Non polar molecules

A

have equal charge distribution and are symmetrical molecules

31
Q

types of shapes

A

linear, tetrahedral, bent, pyramidal

32
Q

Polar molecules

A

have unequal/uneven charge distribution and are not symmetrical

33
Q

SNAP

A
  • Symmetrical - non polar molecule
    Asymmetrical - polar molecule