Structure and Bonding Flashcards by Hannah Campbell

Name the group 1 elements in order down the group

H, Li, Na, K, Rb, Cs, Fr

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Name the group 2 elements in order down the group

Be, Mg, Ca, Sr, Ba, Ra

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Name the group 3 elements in order down the group

Sc, Y

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Name the group 4 elements in order down the group

Ti, Zr, Hf, Rf

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Name the group 5 elements in order down the group

V, Nb, Ta, Db

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Name the group 6 elements in order down the group

Cr, Mo, W, Sg

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Name the group 7 elements in order down the group

Mn, Tc, Re, Bh

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Name the group 8 elements in order down the group

Fe, Ru, Os, Hs

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Name the group 9 elements in order down the group

Co, Rh, Ir, Mt

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Name the group 10 elements in order down the group

Ni, Pd, Pt, Ds

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Name the group 11 elements in order down the group

Cu, Ag, Au, Rg

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Name the group 12 elements in order down the group

Zn, Cd, Hg, Cn

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Name the group 13 elements in order down the group

B, Al, Ga, In, Ti, Uut

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Name the group 14 elements in order down the group

C, Si, Ge, Sn, Pb, Fl

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Name the group 15 elements in order down the group

N, P, As, Sb, Bi, Uup

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Name the group 16 elements in order down the group

O, S, Se, Te, Po, Lv

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Name the group 17 elements in order down the group

F, Cl, Br, I, At, Uus

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Name the group 18 elements in order down the group

He, Ne, Ar, Kr, Xe, Rn, Uuo

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Define ‘quantize’

To restrict a physical quantity to one of a fixed set of numbers

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What is the experimental evidence for electrons behaving as both a particle and a wave?

The photoelectric effect - Many metals emit electrons when light shines on them. Increasing intensity of light increased number of electron emitted, but not their kinetic energy - So electrons can behave as particles

Davisson and Germer (1925): - Fired electrons at nickel - Electrons diffracted not just reflected - Diffraction is a property of waves

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What is the De Broglie relation?

wavelength = h / mv

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Kinetic energy =

Curvature = 2nd derivative

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What is the typical bond length in a molecule?

100 pm

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A very small wavelength means…

No diffraction

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What is the potential energy of an electron confined to a 1D box?

0 inside the box, infinity at the walls

What is the wavefunction, ψ?

Wave height at point x

When you put an electron in a box...

It behaves as a wave

ψ_n(x) =

Csin(nπx / L) L = length of box n = quantum number C = normaliation constant, value needed to make the integral of this 1

Energy of a wave, E =

n²h² / 8mL²

What is a node?

Locus where the wavefunction is 0

What is ψ²?

The probability of finding the electron at that point

ψ_n,m(x,y) =

2/L sin(nπx/L) sin(mπy/L)

2D: E_n,m =

(n² + m²)h² / 8mL²

Quantum number n =

Orbital size quantum number - principle quantum number

Quantum number l =

Orbital shape quantum number - orbital angular momentum quantum number

Quantum number m_l =

Orbital orientation quantum number - magnetic quantum number

Orbital is another word for...

Hydrogen wavefunction, ψ

What does it mean to say that the electron can behave as a wave as long as it's a standing wave?

The wave must be continuous, and there must be an integral number of waves around the ring

2πr =

nλ

What is the radial wavefunction?

- Depends on radius, r - Quantum number n= 1,2,3,4...infinity - Uses symbol ψ(r)

What is the angular wavefunction?

- Depends on θ, ϕ - Quantum numbers l (0,1...n-1) and m (-l,....,+l) - Uses the symbol ψ(θ,ϕ)

What is needed to give a wavefunction in spherical polar coordinates?

Radius, r Colatitude (angle down from z axis), θ Azimuth (angle east from x-z plane), ϕ

What quantum numbers give a 1s wavefunction?

n=1, l=0, ml =0 (s means l = 0)

Radial distribution function =

4πr²ψ² The probability of finding the electrons in all directions at that radius

How many radial nodes does an ns wavefunction have?

n-1

How many radial nodes does an np wavefunction have?

n-2

How many radial nodes does an nd wavefunction have?

n-3

Total wavefunction =

ψ(r)ψ(θ,ϕ)

Angular wavefunctions for all s wavefunctions are...

Spherical

What is the boundary surface?

A representation of the angular wavefunction that contains 90% of the electron density

What does it mean for 2 energy states to be degenerate?

They have the same energy

What is the Pauli Exclusion Principle?

No two electrons in an atom or ion can have all their quantum numbers the same

What is Hand's rule of maximum spin multiplicity?

Lowest energy = Maximum number of parallel spins

For hydrogen, orbital energy is proportional to

-1/n²

For atoms other than hydrogen, orbital energy is proportional to

- Z_eff²/n²

Order of repulsion of pairs of electrons (strongest to weakest)

Lone pair - Lone pair Lone pair - Bonding pair Bonding pair - Bonding pair

Shape of molecule with 2 electron pairs

Linear

Shape of molecule with 3 electron pairs

Trigonal planar

Shape of molecule with 4 electron pairs

Tetrahedral

Shape of molecule with 5 electron pairs

Trigonal bipyramid

Shape of molecule with 6 electron pairs

Octahedral

Shape of molecule with 7 electron pairs

Pentagonal bipyramid

For a trigonal bipyramid, which is the larger site?

Equatorial

For a pentagonal bipyramid, which is the larger site?

Axial

What is Bent's rule? (VSEPR)

The smaller atom goes to the smaller site

Why do we need to create orbital hybrids?

Because for overlap we need singly occupied orbitals

What hybridisation does forming a linear molecule require?

What hybridisation does forming a trignal planar molecule require?

sp² - Taking s, p_x and p_y produces 3 hybrids at 120^o in the xy plane

What hybridisation does forming a tetrahedral molecule require?

sp³ - Taking s, p_x, p_y and p_z produces 4 hybrids directed at the vertices of the tetrahedron

The antibondig orbital is denoted by...

σ_u^* or π_g^*

The bonding orbital is denoted by...

σ_g or π_u

Bond order =

(no. of bonding electrons - no. of antbonding electrons) / 2

What does paramagnetic mean?

A material is paramagnetic if it attracted to a magnet because of unpaired electrons

What does diamagnetic mean?

A material is diamagnetic if it is repelled by a magnet because of paired electrons

Molecular orbitals are...

Linear combinations of atomic orbitals

Magnetic moment, χ =

diamagnetic - paramagnetic

For diatomic molecules with p orbitals, σ_u^* =

1 /√2 [p_z(a) + p_z(b)]

For diatomic molecules with p orbitals, σ_g =

1/√2 [p_z(a) - p_z(b)]

For diatomic molecules with p orbitals, π_{u =}

1/√2 [p_x(a) + p_x(b)]

For diatomic molecules with p orbitals, π_g^* =

1/√2 [p_x(a) - p_x(b)]

Bond order will correlate with...

Bond length and bond strength

J in SI base units

kg m² s^-2

What is excitation energy?

The energy required to move an atom to its next energy level

1 mile =

1609 m

Which is more penetrating, 2p or 2s?

If an orbital is more penetrating, it feels...

A higher Z_eff

What is penetration?

The attraction an orbital feels towards the nucleus

How to show if an orbital has a higher Z_eff than another

Sketch the radial distribution functions, whichever has a local maximum closest to the nucelus feels a higher Z_eff

State and explain for which elements sp switching occurs

B,C and N 2p orbitals are not involved with elements before B, after N, the energy gap between 2s and 2p is too large