Unit 2 - Mr Shah Flashcards by Joe Farmery

Define Relative Isotopic Mass

The mass of an atom of an isotope compared with 1/12 of carbon -12

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Define an Isotope

Atoms of the same element with the same number of protons but a different number of neutrons and different masses

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Define An Orbital

The region where an electron is

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Define First Ionisation Energy

The energy required to remove one mole of electrons (to infinity) from one mole of gaseous atoms to form one mole of gaseous positive ions

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Define a Covalent Bond

The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atom

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Define a Dative covalent bond

A shared pair of electrons in which ONLY one of the bonded atoms provides the bonded pair

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Define Ionic Bonding

The electrostatic attraction between positive and negative ions

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Define electronegativity

A measure of the attraction of a bonded atom for the pair of electrons in a covalent bond

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Define a Dipole

A separation in electrical charge so that one atom of a polar covalent bond, or one end of a polar molecule, has a small positive charge, and the other has a small negative charge

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Define a permanent Dipole

A small charge difference that doesn’t change across a bond, with partial charges on the bonded atoms: resulting in the bonded atoms having different electronegativities.

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What is the name and angle of a compound with 2 electron pairs?

Linear, 180 degrees

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What is the name and angle of a compound with 3 electron pairs?

Trigonal Planar, 120 degrees

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What is the name and angle of a compound with 4 electron pairs?

Tetrahedral, 109.5 degrees

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What is the name and angle of a compound with 5 electron pairs?

Trigonal Bipyramidal, 90 and 120 degrees

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What is the name and angle of a compound with 6 electron pairs?

Octahedral, 90 degrees

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With what 3 atoms does hydrogen bonding take place?

N,F and O

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What is the relative mass and charge of a proton?

1 and +

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What is the relative mass and charge of a neutron?

1 and 0 (neutral)

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What is the relative mass and charge of an electron?

1/2000 and -

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What do we use a mass spectrometer for?

To weigh atoms in a compound to find their abundance

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What is the equation for Relative atomic mass from a mass spectrometer?

the sum of(relative atomic mass x abundance) / 100

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How do you find the maximum number of electrons on each shell?

2n^2 where n is the shell number

Name the full order up to 4f of the sub-shells

1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 4d, 4f

How many electrons does an s sub-shell hold?

How many electrons does a p sub-shell hold?

How many electrons does a d sub-shell hold?

How many electrons does an f sub-shell hold?

What are the exceptions to the rule and how are they different?

Cr as it goes 4s^1, 3d^5 instead of 4s^2, 3d^4 Cu as it goes 4s^1, 3d^10 instead of 4s^2, 3d^9 This is because the 4s and 3d levels are very close in energy.

How do you draw short structures of electronic arrangements?

Use noble gases. E.g. Lithium is 1s^2, 2s^1 | but [He] has an electronic arrangement of 1s^2 so we can draw it as [He] 2s^1

What 3 factors affect the ionisation energy?

- Amount of shielding by shells - Distance from the positively charged nucleus (atomic radius) - Number of protons

Why going across periods is there sometimes a dip in ionisation energy, eg. from Neon to sodium?

Either: - It's an electron in it's own sub-shell so easier to remove - It's an electron with another electron in an orbital so they repel - The electron moves into the next shell, so shielding is less and distance from the nucleus is more

Write the equation for the first ionisation energy of Li

Li ---> Li+ + e- | g) (g

Write the equation for the first ionisation energy of Al

Al ---> Al+ + e- | s) (s

Write the equation for the second ionisation energy of Li

Li+ ---> Li2+ + e- | g) (g

Name the giant covalent molecules

Diamond and Graphite

Name a few properties of Metallic compounds Refer to M.P , conductivity and strength

High M.P - Ease of separation depends on density of electron cloud and ionic charge Malleable and Ductile - The electron clouds BIND ions together Does conduct - There are mobile/free electrons that can carry a charge GIANT STRUCTURE Electrostatic attraction between postive and negative ions (put in exam)

Name a few properties of simple covalent compounds Refer to B.P , conductivity and solubility

Low B.P - Only have WEAK Van der Waals forces which means little energy is required to break them Doesn't conduct - No free electrons Solubility - Tends to be in organic solvents than water ATTRACTION BETWEEN MOLECULES INCREASE AS THE MOLECULES GAIN ELECTRONS

Name a few properties of ionic compounds Refer to M.P ,Strength, conductivity and solubility

Very high M.P - Strong electrostatic attraction Very Brittle - Any distortion leads to layers moving and similar ions being next to each other, which repel and crack the crystal Doesn't conduct when solid - ions held in a lattice DOES conduct when MOLTEN or in AQUEOUS solution - Has free electrons Only soluble in water

Name a few properties of giant covalent structures Refer to M.P ,Conductivity and strength

Very High M.P - Lattice is made up of large number of covalent bonds, which must all be broken Doesn't conduct - No free electrons BUT... Graphite does conduct as each C is only uses 3 outer electrons to bond. The other can carry a charge Strength - Diamond is a hard, rigid structure Graphite is soft as it is in layers which can slide

What is the formula of ammonia?

NH3

What are the formulas of a nitrate and a nitrite

No3- and No2-

What are the formulas of a sulphate and a sulphite?

So4 2- and So3 2-

What do we use to predict ionic formula?

The group of the element Eg. if an element is in group 2, the charge is 2+ if an element is in group 7, the charge is 1-

What is the pair of electrons called that we use in dative covalent bonds?

A lone pair

What must we look for when determining the strength of ionic bonds?

Charge and atomic radius (smaller is stronger)

What must we look for when determining the strength of metallic bonds?

The atomic radius (smaller means stronger), charge and the number of delocalised electrons

What is the most electronegative element?

Fluorine | Cl, N and O are very electronegative aswell

What happens to the electron pair when an element is a lot more electronegative?

They move to the more electronegative element, and so it gets a partial negative charge The bond would then be POLAR

Would CCL4 be polar?

No as it is symmetrical

Would Cl2 be polar?

No as the 2 chlorines have the same pulling power

Can permanent dipole-dipole interaction happen ONLY in ionic or covalent bonds?

Covalent molecules, e.g HCl

How does the number of electrons affect Van der Waals forces?

More electrons = Stronger Van der Waals forces

Name an anomalous property of water

Ice is less dense than water (H bonds hold water molecules apart) Water has a RELATIVELY high M.P/B.P Relatively high surface tension

Define Relative Atomic Mass

The weighted mean mass of an atom compared with 1/12 of the mass of carbon -12