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Chemistry > Elements Of Life > Flashcards

Elements Of Life Flashcards

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1
Q

What is Avogadro’s constant?

A

One mile of any substance contains 6.02x10(23) formula units.

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2
Q

What is the mass, mol, mr equation?

A

Mol x Mr

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3
Q

What is the mole concentration equation?

A

Vol x Concn

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4
Q

How do you find the percentage composition of a compound?

A

% of each element =

Ar of element x no. of atoms of element in formula
———————————————x100
Mr of compound

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5
Q

How do you measure the mass of solids?

A

Revisit

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6
Q

What are the shapes of the S and P orbitals?

A

S orbital is spherical

P orbital has a figure 8 shape on three axis’ (xyz)

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7
Q

What is true about fusion reactions?

A

Lighter nuclei always join to give heavier nuclei under conditions of high temperature and pressure.

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8
Q

What are cations?

A

Positively charged ions

Mostly metals that want to lose e-

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9
Q

What are anions?

A

Negativity charged ions

Mostly non-metals that want to gain e-

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10
Q

What is ionic bonding?

A

Bonding between metals and non-metals to form ions (cations or anions) when the overall energy change for the reaction is favourable.

The transferral of e- from metals to non-metals.

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11
Q

Can ionic bonds/molecules/compounds form a giant lattice?

A

Yes.

The oppositely charged ions attract each other and build up to form a giant lattice.

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12
Q

Three properties of simple molecular structures

A
  1. Low melting points
  2. Do not conduct electricity
  3. Usually insoluble in water
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13
Q

What is a dative bond and how is it shown?

A

When both bonding e- come from the same atom.

Shown using an arrow pointing away from the donating atom.

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14
Q

What are the two covalent structures?

A
  1. Covalent molecular structures

2. Covalent network structures

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15
Q

What is the difference between ionic and covalent bonding?

A

Ionic: when metals on the left-hand side of the periodic table combine with non-metals on the right ( ionic compounds are formed)

Covalent: when non-metals on the right- hand side of the periodic table combine with each other ( covalent compounds are formed)

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16
Q

What are covalent molecular structures?

A
  • they consist of individual molecules
  • covalent bonds within the molecule are strong whilst bonds between molecules are weak
  • the strength of the imf. determines whether the substance is a gas, solid or liquid (@ norm. temp. )
17
Q

What are some of the properties of covalent molecular structures?

A
  • low m.p and b.p
  • doesn’t conduct electricity
  • usually insoluble in water unless bonded to a group which does hydrogen bonding
18
Q

What are covalent network structures?

A

• consist of repeating lattices of covalently bonded atoms

19
Q

What are some properties of covalent network structures?

A
  • insoluble (solids)
  • high m.p and b.p
  • doesn’t conduct electricity
20
Q

What is Metallic bonding?

A

When metal armies lose their e- to form a lattice of regularly spaced positive ions.

The outer e- from each atom contribute to a common pool of e- which randomly move throughout the lattice of +ve ions.

The e- don’t belong to any specific atom therefore are delocalised.

21
Q

What is a metallic bond?

A

The attraction of +ve charged ions in the metal to the -be charged delocalised e-

The strength of metallic bonding depends on the no. of e- per atom available for delocalisation

22
Q

What are some properties of metallic bonding?

A
  • high m.p
  • insoluble in water
  • conducts electricity when solid or liquid
23
Q

Does density increase or decrease across a period?

A
  • it increases
  • elements with high densities contain heavy particles which are closely packed together so that they occupy a relatively small volume.
  • in period 2 the density increases then falls at boron
  • in period 3 the density increases then falls at aluminium
24
Q

Does the m.p and b.p increase or decrease across a period?

A
  • increases
  • when an element is melted then boiled, the bonds between their particles must be overcome.
  • the strength of these bonds influence whether an element has a high or low m.p or b.p
  • in period 3 it stops at silicon
  • no. of protons in nucleus increase therefore electrons are pulled in closer (mostly for metals)
25
Q

Does atomic size increase or decrease down a group?

A
  • increase

* another electron shell is added as you down a group so the size of the atom will increase

26
Q

Does atomic size increase or decrease across a period?

A
  • decreases
  • successive e- added across a period enter the same electron shell.
  • the no. of protons increases across the period which increase the +ve nuclear charge which attracts the e- more and more strongly (as a result the atoms get smaller even though they have more e-)
27
Q

What is (first) ionisation enthalpy?

What is the general equation?

A
  • the energy needed to remove one e- from every atom in one mole of isolated gaseous atoms of the element.
  • a mole of gaseous ions with one positive charge are formed.
  • X(g)——>X+(g) + e-
28
Q

Do ionisation enthalpies increase or decrease down a group?

A
  • decrease

* attraction between the nucleus and the outermost e- decreases as a new e- shell is added each time

29
Q

What is a standard solution?

A

Any solution that has a known concn

30
Q

Outline the steps of making up a standard solution.

A
  1. Calculate the mass of solute required and weigh it out.
    n mass
    ——— ————
    c x v Mr x mol
  2. Pour as suitable volume of distilled water into a 250cm3 beaker.
  3. Transfer the weighed solute into the beaker and dissolve.
  4. Transfer the solution to a 250cm3 volumetric flask using a funnel making sure that all of the washings are transferred.
  5. Make up to the 250cm3 mark using distilled water whilst using a dropping pipettes for the last 1cm3 so that the bottom of the meniscus touches the line.
  6. Stopper the flask and invert it a few times to ensure complete mixing.
31
Q

Do ionisation enthalpies increase or decrease across a period?

Why?

A
  • increase
  • the no. of +ve protons in the nucleus increases meaning that there is a greater attraction between the nucleus and the outer e-
32
Q

As you go down group 2 what is true of their hydroxides, sulphates and thermal stability of carbonates?

A

Hydroxides: become more soluble as you go down group 2

Sulphates: become less soluble as you go down group 2

Thermal stability of carbonates: carbonates become more thermally stable as you go down group 2

Chemistry (7 decks)

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