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13A/Ch1 > 2.1 Atoms & Reactions > Flashcards

2.1 Atoms & Reactions Flashcards

1
Q

Names in order of those involved in the history of the atom?

A 
Dalton
JJ Thomson
Rutherford(& Marsden)
Bohr
Chadwick
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2
Q

What was stated in Dalton’s atomic theory? (4)

A
  • Atoms are tiny particles made of elements
  • Atoms cannot be divided
  • All the atoms in a element are the same
  • Atoms of one element are different to those of other elements
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3
Q

What did Thompson discover about electrons? (3)

A
  • They have a negative charge
  • They have very small mass
  • They can be deflected by magnet and electric field
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4
Q

Explain the plum pudding model

A

Atoms are made up of negative electrons moving around in a sea of positive charge

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5
Q

What were Rutherford’s proposal after the gold leaf experiment? (3)

A
  • Most of the mass and positive charge of the atom are in the nucleus
  • Electrons orbit the nucleus
  • Overall positive and negative charges must balance
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6
Q

What’s an Isotope?

A

Atoms of the same element with different number of neutrons

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7
Q

Why does different isotopes of the same element react in the same way?

A
  • Neutrons have no impact on the chemical reactivity

* Reactions involve electrons, isotopes have the same number of electrons in the same arrangement

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8
Q

What’s an Ion?

A

Charged particles formed when atoms lose or gain electrons

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9
Q

Define relative atomic mass

A

The weighted mean mass of an atom of an element compared with one twelfth of the mass of an atom of carbon -12

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10
Q

Define relative isotopic mass

A

The mass of an atom of an isotope compared with one twelfth of the mass of an atom of carbon-12

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11
Q

What’s the unit and symbol for ‘Amount of substance’?

A

n, Mole or mol

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12
Q

What is Avogadro’s constant?

A

6.22*10^23

the number of atoms per mol of n isotope of carbon 12

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13
Q

Equation for mol?

A

Mass(g) / MR

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14
Q

Define empirical formula

A

Simplest whole number ratio of atoms of each element present in a compound

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15
Q

How would ya calculate empirical formula? (3)

A
  1. find mole ratio of each substance
  2. divide each ratio by smallest number
  3. multiply to make sure all ratios integers
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16
Q

what’s Avogadro’s law?

A

At room temperature and pressure a mole of any gas would occupy the same space (24dm3)

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17
Q

At room temperature an pressure(RTP) the volume of a gas is….

A

n=v/24
or
n=v/24,000
*depending on if V is in dm3 or cm3

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18
Q

What’s the ideal gas equation?

A

pV=nRT

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19
Q

What are the units for each symbol in the ideal gas equation?

A 
p=pressure= in pa, if atm the convert to 101325 pa
V=volume= in M3 (divide dm3 by 1000)
n=number of moles
R=gas constant
T=temperature= in K(c+273)
20
Q

What the equation for concentration?

A

c=n/v
c=concentration (mol dm-3 or mol cm-3)
n= mole
v=volume (can be cm3 or dm3)

21
Q

What’s the difference between concentrated and dilute solutions?

A

concentrated - lots of solute per dm3

dilute - little solute per dm3

22
Q

What does the unit M mean?

A

Molar, for a solution with it concentration in mol dm-3

23
Q

What are the 4 state symbols?

A

(s) solid
(l) liquid
(g) gas
(Aq) aqueous

24
Q

What are the 3 ways to work out moles (from equations)?

A
  • Mass/mr
  • conc * volume
  • volume of gas/ 24dm3 (or 2400cm3)
25
Q

What is percentage yield?

A

Measure of the moles of a product formed in relation to the reactant consumed

26
Q

Equation for percentage yield?

A

Actual amount of product in mol/
Theoretical amount of product in mol

  • normally given actual and need to work out theoretical
27
Q

What is Atom economy ?

A

A measure of the amount of starting materials that end up as useful products.

28
Q

Equation for Atom economy?

A

Mr of desired product/ sum of Mr all products

*100 to get a percentage

29
Q

How does the type of reaction affect atom economy

A
  • Addition reaction = 100% atom economy

* Elimination or substitution = less than 100%

30
Q

What’s an acid?

A
  • Proton donors, disassociate to form H+,
  • Dissolves in water forms solutions with ph<7
  • Neutralise bases
31
Q

What’s a base?

A
  • Proton acceptors,
  • Dissolve in water to form alkalis with ph >7
  • Neutralise acids
32
Q

What’s an alkali?

A

Substance that gives ph above 7 if dissolved in water

and forms OH- ion, very corrosive

33
Q

What makes an Acid Strong or weak?

A

Determined by how thoroughly they disassociate (give away protons/ H+)

34
Q

What an Amphoteric substance?

A

Substance that can act as an Acid & Base

35
Q

What’s a salt?

A

An ionic compound with a cation(positive) and anion (negative)

36
Q

How do salts form?

A

neutralisation reactions between acids and bases.
bases can be:
• Alkalis (forms salt and water)
• Metal oxides (forms salt and water)
• Carbonates (forms salt and water and CO2)
*if only a metal used forms salt & Hydrogen

37
Q

What’s the difference between Anhydrous and Hydrated crystals?

A
  • Anhydrous= no water

* Hydrated= water in crystal structure

38
Q

What is water of crystallisation?

A

Water molecules in hydrated crystals, that form part of the crystalline structure

39
Q

How would you determine a hydrated salts formula?

A
  • Calculate mol of anhydrous salt
  • Calculate amount of water (in mol)
  • Determine formula
40
Q

What is titration?

A

when you measure the volume of one solution that reacts with another
* Must know concentration of at least 1 of the solutions

41
Q

How to carry out a titration(4)

A
  1. pipette measured volume of a solution into conical flask, add indicator
  2. place other solution in burette, record start line
  3. add burette solution to flask solution till reaction just complete (end point)
  4. meausre volume of solution added From the burette
42
Q

What are indicators?

A

mixtures/compound that INDICATE a reactions endpoint

43
Q

What’s the colour changes of methyl orange?

acid→end point→base

A

Red(Acid)→ Orange(end point)→ Yellow(Base)

44
Q

What’s the colour changes of Phenothalien?

acid→end point→base

A

colourless (Acid)→pale pink(end point)→ pink(Base)

45
Q

Oxidation and reduction are….

A

Oxidation Is Loss of electrons
Reduction Is Gain of electrons

*Oxidation is also the gain of oxygen
Reduction is also the loss of oxygen

46
Q

Uncertainty eq?

A

(absolute uncertainty *2)/ value measured

13A/Ch1 (6 decks)

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