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12U Chemistry > Structures and Properties > Flashcards

Structures and Properties Flashcards

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1
Q

T/F: An atom’s inner core – the noble gas inner core –
does not form bonds.

A

True!!

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2
Q

What was the name of the American chemist that developed what we call now “Lewis Structures”

A

Gilbert
Lewis (1875-1946)

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3
Q

A Lewis Structure is one of the best ways to represent molecules in a ___ dimensional form

A

2 dimensional form

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4
Q

Each atom, bonding pair, and lone pair of electrons takes up space and affects the _______ of the molecule.

A

Structure of the molecule

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5
Q

T/F: When drawing lewis structures, you position MOST electronegative atom at centre of the molecule and the remaining elements go around this central atom.

A

FALSE!!

The LEAST electronegative atom is at the centre.

Atoms with higher electronegativity are generally more unwilling to share its electrons - which is not wanted.

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6
Q

T/F: One of the first steps in drawing a lewis diagram is to determine total number of ALL electrons in all the atoms in the molecule.

A

FALSE!!

Its only the VALENCE electrons that are counted.

For polyatomic ions, add or subtract electrons according to the charge.

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7
Q

What is the octet rule?

A

The octet rule refers to the tendency of atoms to prefer to have eight electrons in the valence shell.

(they are most stable when the valence shell is filled)

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8
Q

What is formal charge?

A

The difference in electrical charge between the valence electrons in an isolated atom and the number of electrons assigned to that atom in a Lewis structure.

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9
Q

How do you calculate overall charge of a molecule?

A

The sum of all formal charges within a molecule determines the overall charge of a molecule.

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10
Q

What is the equation for formal charge?

A

Formal Charge = (# of e- the atom should have) – (# of e- the atom does have)

Think about it this way:

how many Ve- it brings - lone pairs - electrons bonded to it

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11
Q

What is the exception of “Expanded Octets”?

A

For some molecules, bonding at the central atom is best explained by a model that shows a central atom that has more than eight electrons in the valence shell (expanded
valence)

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12
Q

What is the exception of “Incomplete Octets”?

A

Some metals (Be and B) can form covalent bonds with halogens
* They are said to have an incomplete valence, but are stable molecules

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13
Q

What is the exception of “Resonance Structures”?

A

A resonance structure is one of two or more Lewis structures that show the same relative position of atoms, but different positions of electron pairs.

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14
Q

What are Co-ordinate Covalent Bonds?

A

A covalent bond where the central atoms donates both electrons to the shared pair of electrons.

  • Once the bond is formed, it behaves the same
    as any other bond.
  • So the coordinate covalent bond is not shown
    in the Lewis structure.
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15
Q

Which statement is not apart of Dalton’s Postulates on Matter?
A) Elements are made of extremely small particles called atoms.
B) Atoms of a given element are identical in size, mass, and other properties; atoms of different elements differ in size, mass, and other properties.
C) Atoms cannot be subdivided, created, or destroyed.
D) Atoms of different elements combine in simple whole-number ratios to form chemical compounds.
E) In chemical reactions, atoms are solely combined to form new products

A

E!!!

Dalton states that in chemical reactions, atoms are not only combined, but also
separated, or rearranged.

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16
Q

What was Dalton’s contribution to the Modern Atomic Theory?

A

→ He began to make measurements of the
masses of elements
→ Created a simple table of elements
→ He determined that ratios of elements created new compounds
-→His Five Postulates on Matter

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17
Q

What was Dalton’s Atomic Theory? What problems came with this theory?

A

He suggested that an atom is a solid featureless sphere (billard ball model).

The problems involved the exclusion of subatomic particles and the electrical properties present within an atom.

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18
Q

What was JJ Thomson’s contribution to the Modern Atomic Theory?

A

→ The cathode ray tube experiment
- He bent the flow of particles using
a magnet
→He discovered the first subatomic particle, THE ELECTRON!!!!!!
→He concluded that electrons were very small (1/2000th the size of a [H] atom)

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19
Q

What was JJ Thomson’s model of the atom? What did Thomson’s model fail to explain?

A

Thomson’s “plum pudding” model consisted of a positively charged sphere containing negatively charged electrons embedded in the sphere. He suggested the resulting atom would either be neutrally charged or uncharged.

Thomson’s model failed to explain:
- how the positive charge holds on the electrons inside the atom
- An atom’s stability
- The presence of a nucleus in the atom.

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20
Q

What contributions did Ernest Rutherford have on the Modern Atomic Theory?

A

✦ The GOLD FOIL EXPERIMENT
- Discovered atoms contain a NUCLEUS
✦ Determined that there is more than
one radioactive particle ( α, β, and γ)
✦ Discovered the PROTON!!!

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21
Q

What limitations came with Rutherford’s model?

A

An electron accelerating around the nucleus would continuously emit electromagnetic radiation and lose energy, thereforing falling into the nucleus.

(However, this is not consistent with real-world observations – atoms are stable)

22
Q

Who is James Chadwick quite literally? Why?

A

JIMMY NEUTRON

This is because he discovered the NEUTRON. He stated that at least half of mass of the nucleus was unaccounted
for, proving that there must be a neutral mass within the nucleus.

23
Q

What is a quanta?

A

The amount of energy needed for a photon (or an electron) to move from one energy level to another. This would result in a “quantum leap.”

24
Q

What did Niels Bohr’s model of hydrogen describe about electrons?

A
  • They follow circular orbits
  • They can only exist in certain “allowed” orbits or energy levels
    (energy of electrons is quantized)
  • They do not radiate energy while in one orbit
  • They can jump between orbits by gaining or losing a specific amount of energy
25
Q

What were the successes and weaknesses of Bohr’s model?

A

Success:
1) Bohr’s mathematics perfectly explained all the observations for Hydrogen
2) This is a major success for Quantum Mechanics – to this day it has never failed
3) He solved Rutherford’s problem

Weaknesses:
1) Bohr’s method only worked for
Hydrogen
2) Although the quantum theory of
light was experimentally proven,
other experiments had proven that
light had also continuous wavelike
properties.

26
Q

Who did Bohr work with to give birth to the idea of Quantum Physics and Chemistry?

A

Max Planck (and his teacher Kirchhoff)

27
Q

What statement did Louis de Broglie reverse?

A

“Sometimes it behaved like a continuous electromagnetic wave and sometimes it behaved like a particle” was reversed into…

“If a wave can behave as a particle, then a particle should also be able to behave like a wave.

28
Q

What was Louis de Broglie’s main contribution to the Quantum Atomic Theory?

A

He introduced the idea that particles, such as electrons, could be described not only as particles but also as waves

29
Q

What was Erwin Schrödinger’s main contribution to the Quantum Atomic Theory?

A

Erwin Schrödinger formulated a wave equation that accurately calculated the energy levels of electrons in atoms.

30
Q

What did Schrödinger’s equation not tell us about?

A

It didn’t describe WHERE the electrons are and WHAT they are doing.

31
Q

What was Werner Heisenberg’s main contribution to the Quantum Atomic Theory?

A

Heisenberg’s Uncertainty Principle

32
Q

What did Heisenberg’s Uncertainty Principle state?

A

✰ it is IMPOSSIBLE to simultaneously know the exact position and speed of a particle
✰ The best one can do is predict the electron probability density

33
Q

What did Paul Dirac contribute to the Quantum Atomic Theory?

A

He devised a form of quantum mechanics developed by Schrodinger and Heisenberg which provides the laws of motion that govern atomic particles.

34
Q

What are the charcteristics of the S Orbital?

A

➵ 1 Spherical shape
➵ Holds up to two electrons

35
Q

What are the charcteristics of the P Orbital?

A

➵ Dumb-bell shaped
➵ 3 different orientations on each axis
➵ Holds up to 6 electrons

36
Q

What are the charcteristics of the D Orbital?

A

➵ 5 different configurations, 4 having a cloverleaf shape and 1 having a donut with a dumb-bell in the middle
➵ Holds up to 10 electrons

37
Q

True or False: F Orbitals have more complex configurations than S, P and D orbitals.

A

True

38
Q

What does Aufbau’s Principle state?

A

Electrons fill orbitals starting with the lowest energy level.

39
Q

What does the Pauli Exclusion Principle state?

A

No two electrons can fill the same orbital with the same spin. only two electrons with opposite spins can occupy any one orbital.

40
Q

What does Hund’s rule state?

A

For orbitals of the same type, electrons fill each orbital singly before any orbital gets a second electron.

41
Q

How would you write a condensed electron configuration?

A

Use a noble gas “core” in square brackets followed by the next energy levels being filled.

42
Q

What is covalent bonding?

A

The sharing of electrons between atoms of non-metal elements (ΔEN < 1.7)

43
Q

What does Valence Bond Theory state?

A

1) A covalent bond will form when half filled orbitals of one atom overlap with half filled orbitals of another
(Connects to Pauli’s Exclusion Theory)
2) Wherever there is an overlap of orbitals, there is a location of high electron density

44
Q

What are the two types of overlaps?

A

Sigma Bonds (𝝈) and Pi Bonds (π)

45
Q

What are the characteristics of a Sigma Bond?

A
  • Head on overlap
  • Represented as a single bond in lewis structures
  • Ability to hybridize
46
Q

What are the characteristics of a Pi Bond?

A
  • Side by side (parallel) overlap of p orbitals
  • Unhybridized
  • Forms a “bridge” like structure.
47
Q

T or F: Pi Bonds are stronger than Sigma Bonds.

A

False!!!

Pi bonds have less of an overlap, making the second or third bond easier to break.

48
Q

What can get hybridized?

A

Sigma bonds and lone pairs

49
Q

What does VSEPR stand for?

A

Valence Shell Electron Pair
Repulsion

50
Q

What does the VSEPR theory explain?

A

VSEPR theory explains and predicts the geometry of molecules by counting pairs of electrons that repel each other to minimize repulsion.

12U Chemistry (5 decks)

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