Topic 2 - Ionic Compounds and Analysis Flashcards

1
Q

What is ionic bonding?

A

When atoms transfer (lose or gain) electrons to form charged (+vley or -vely) atoms (/group of atoms) called ions. As opposite charges attract, the ions are strongly attracted to one another

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2
Q

Why do atoms transfer electrons?

A

To try to get a full outer shell

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3
Q

How do sodium and chlorine bond together?

A
  • Sodium atom gives outer electrons to chlorine (Na+, Cl-)

- Opposite charges attract so attracted together as ionic bond

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4
Q

What Groups’ atoms most readily form ions?

A

1, 2, 6, 7

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5
Q

How do Group 1 + 2 elements form ions?

A
  • Lose electrons
  • Positively charged ions
  • Cations
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6
Q

How do Group 6 + 7 elements form ions?

A
  • Gain electrons
  • Negatively charged ion
  • Anions
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7
Q

What charge do anions have?

A

Negative

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8
Q

What charge do cations have?

A

Positive

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9
Q

On the periodic table, where do two elements have to be to form ionic bonds with one another?

A

On opposite ends of the periodic table

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10
Q

How does magnesium and oxygen form an ionic bond?

A
  • Magnesium gives 2 outer electrons (Mg2+)
  • Oxygen takes electrons (O2-) (oxide ion)
  • Forms MgO, magnesium oxide
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11
Q

How does sodium and oxygen form an ionic bond?

A
  • 2 sodium give outer electron (2xna2+)
  • Oxygen takes 2 electrons (O2-)
  • Na2O
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12
Q

How does calcium and chlorine form an ionic bond?

A
  • Calcium transfers 2 outer electrons (1 to each chlorine: Ca2+, 2x Cl-)
  • CaCl2
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13
Q

What kind of structures do ionic compounds have?

A

Regular lattice

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14
Q

How does an ionic regular lattice form?

A
  • Ions form closely packed regular lattice arrangement
  • Due to ionic bonds having strong electrostatic forces of attraction between oppositely charged ions
  • Ionic compounds all have similar properties because of their structrue
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15
Q

What are the properties of an ionic compound?

A
  • High melting point
  • High boiling point
  • Conduct electricity when aqueous or molten
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16
Q

Why do ionic compounds have high melting points and high boiling points?

A
  • Due to the very strong bonds between the ions

- Takes a lot of energy to break these bonds

17
Q

Why do ionic compounds conduct electricity when aqueous or molten?

A
  • Ions are separate + free to move so carry electric current

- Ions are held rigid in solid so aren’t free to move so can’t conduct electricity

18
Q

What are the two rules when naming a compound?

A
  • When 2 different elements combine compound’s name is ‘something -IDE’
  • When 3 or more different elements combine + 1 is oxygen, compound’s name is ‘something -ATE’
19
Q

What is the solubility rule for common salts of sodium, potassium and ammonium?

A

Soluble (-carbonates, hydroxides)

20
Q

Which salts of sodium, potassium and ammonium are insoluble?

A

Carbonates and hydroxides

21
Q

What is the solubility rule for all nitrates?

A

Soluble

22
Q

What is the solubility rule for common chlorides?

A

Soluble (-silver, lead)

23
Q

Which chloride salts are insoluble?

A

Silver chloride + lead chloride

24
Q

What is the solubility rule for common sulfates?

A

Soluble (-lead, barium, ammonium)

25
Q

Which sulfate salts are insoluble?

A

Lead sulfate, barium sulfate + calcium chloride

26
Q

What is the solubility rule for common carbonates and hydroxides?

A

Insoluble (-sodium, potassium, ammonium)

27
Q

How do you make a pure, dry sample of an insoluble salt by a precipitate reaction?

A

-Precipitation reaction: pick 2 soluble salts + react together
-E.g. lead chloride: lead nitrate + sodium chloride (both soluble)
Method:
1) - 1 spatula Pb(NO3)2 to test tube + fill w/ distilled water. Shake thoroughly so all dissolves. Same w/ NaCl (dist. water ensures no other ions)
-Tip 2 solution into small beaker, stir so all mixes. PbCl should precipitate out
2) - Put filter paper into filter funnel, into conical flask
-Pour contents through
-Swill out beaker w/ dist. water, tip into beaker (ensures all product from beaker)
3) - Rinse all contents of filter paper w/ dist. water so all soluble sodium nitrate is washed away
-Scrape lead chloride onto fresh filter paper + leave to dry

28
Q

How could you make a pure, dry sample of barium sulfate (BaSO4), an insoluble salt?

A
  • Mix solution of barium ‘something’ + ‘something’ sulfate (as long as both soluble, e.g. barium nitrate + potassium sulfate)
  • Filter out precipitate of barium sulfate
  • Wash w/ dist. water (remove impurities)
  • Dry on filter paper
29
Q

How can barium sulfate be used for X-rays?

A
  • Normally, only bones show in X-rays
  • Barium sulfate is opaque to X-rays; when drunk shows up gut so any problems i.e. blockages can be seen
  • Barium salts are toxic, but barium sulfate can be drunk safely as insoluble, so isn’t absorbed into bloodstream, just passes though body
  • When patient drinks barium sulfate before X-ray, known as barium meal
30
Q

What colour flame do sodium ions (Na+) produce in the flame test?

A

Yellow/orange flame

31
Q

What colour flame do potassium ions (K+) produce in the flame test?

A

Lilac flame

32
Q

What colour flame do calcium ions (Ca2+) produce in the flame test?

A

Brick-red flame

33
Q

What colour flame do copper ions (Cu2+) produce in the flame test?

A

Blue-green flame

34
Q

How would you do a flame test in a lab?

A
  • Dip clean wire loop into sample of compound + put into clear blue part of Bunsen flame (hottest part)
  • Make sure wire loop is really clean by dipping into HCl + rinsing with dist. water
35
Q

How do you test for carbonates (CO3 [2-])?

A

-React carbonate w/ dilute acid
-Bubble gas produced through limewater, as if carbonate, CO2 released which turn limewater cloudy
acid+carbonate–>salt+water+carbon dioxide

36
Q

How do you test for sulfate ions (SO4 [2-])?

A

-Add dilute HCl, followed by barium chloride, BaCl2
-White precipitate of barium sulfate means original compound was a sulfate
Ba2+ + SO4 [2-] (aq) –> BaSO4 (s}

37
Q

How do you test for chloride ions (Cl-)?

A

-Add dilute nitric acid (HNO3), then silver nitrate solution (AgNO3)
-Chloride give white precipitate of silver chloride
Ag+ + Cl- –> AgCl(s)

38
Q

How can spectroscopy be used to identify elements?

A
  • Patterns of light emitted by elements in a heated sample are analysed
  • Each element present in sample produces different colours
  • Spectroscopy is fast + reliable + can be used to detect even small amounts of elements in a sample
  • Allowed scientists to discover new elements e.g. rubidium + caesium, both discovered as produced patterns of light not seen before