Atomic Structure Intro Flashcards

1
Q

Describe a pure substance

A
  • has constant properties and composition aka. made of one type of atom
  • all matter can be separated into pure substances
  • they can be elements or compounds and are changed via chemical reactions
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2
Q

What is the law of definite proportions?

A

Law that a chemical compound maintains at a fixed ration regardless of source or amount

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3
Q

What is the law of multiple proportions?

A

The law that when 2 elements combine, the ratio of the 1 element that combines with the fixed weight of the element are whole numbers.

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4
Q

Isotope

A

Atoms of same element with different mass no.

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5
Q

Atomic number

A
  • Number of protons (= number of electrons)

- Bottom number for element on periodic table

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6
Q

Mass number

A
  • Number of protons and neutrons combined

- Top number for element on periodic table

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7
Q

What is a unit of mass

A

It is 1/12th of carbon 12 (also called Dalton/D1)

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8
Q

What is relative atomic mass

A

It is the ratio of the mass of one atom of an element against the mass of 1/12th of an atom of carbon 12

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9
Q

What is relative molecular mass?

A

The ratio of the average mass of a molecule to the mass of one 1/12th of an atom of carbon 12

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10
Q

What is Avogrado’s constant?

A

The number of atoms in 12g of carbon 12

6.022045 10^23/mol

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11
Q

What is molar mass (and equation)

A

Molar mass = grams/mole

- sum of the total mass in grams of all the atoms that make up a mole of particular molecule

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12
Q

What is electronegativity? (Describe)

A
  • Tendency of an atom to attract a pair of shared electrons
  • happens for covalent bonds
  • affected by atomic number and the distance of the valence bonds from the nucleus
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13
Q

Homonuclear

A

Multiple molecules of the same element

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14
Q

Heteronuclear

A

Multiple of molecules of different elements

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15
Q

Disassociation energy

A

Energy required to fracture a bond between atoms

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16
Q

What are the 3 different electronegativity scales

A

Pauling scale = mean difference between average disassociation energies homo and heteronuclear compounds of an element

Alfred- Rochow = value of electrostatic force exerted by nuclear charge of valence electrons

Mullikan - average ionisation energy and electron affinity of element

17
Q

Describe an atom

A
  • nucleus positively charged and consists of protons (+) and neutrons (0)
  • shells negatively charged and consist of electrons (-)
  • shells 100,000 times larger than nucleus
  • nucleus contains 99.9% of mass
18
Q

Describe how periodic table can be used to observe ionisation

A
  • Increases across periods as energy also increases to remove electron and atomic radius decreases = greater attraction between electrons and nuclei
  • Decreases as atomic number increases/down a group
  • noble gasses don’t want to react = least likely to ionise
19
Q

Describe relationship between periodic table and electron affinity

A
  • increases across periods
  • sometimes decreases down a group
  • low for noble elements
20
Q

Describe electron shells and sub shells

A
  • shells are discrete (not in between energy transitions)
  • shells contain max 2n^2 electrons
  • shells divide into sub shells S (2 electrons), P (6), D (10), F (14)
  • mains shell 1 = 1s (2 electrons)
  • mains shells 2 = 1s and 1p (8 electrons)
  • mains shell 3 = 1p and 1 d (18 electrons)
  • s shells spherical
  • p shells figure of 8
21
Q

Describe electron orbitals

A
  • function probabilities (95%) of electron being present

- no of sub shells reflect spatial orientation

22
Q

Describe energy levels of electrons

A

divided into 4 quantum numbers, electrons will differ in at least 1 of them:

  • principle quantum number, n (size of orbitals)
  • angular quantum number, l (shape of orbitals)
  • magnetic quantum number, m (orientation of orbitals)
  • spin quantum number, s ( all electrons need different spins.. spins clockwise on axis = spin up, counterclockwise = spin down) if spins unpaired = reactivity
23
Q

How to work the relative atomic mass

A

Add together the mass number of each element

24
Q

How to work out molecular mass

A
  1. Determine molecular formula
  2. Find atomic mass of each element
  3. Multiple atomic mass by number of that element in the molecule
  4. Add values together
25
How to work out the number of moles
Number of moles = mass x relative molecular mass
26
Molar concentration/molarity
Number of moles of a solute that can dissolve in 1 litre of solution
27
Molarity equation
Amount of solute (in moles) / volume of solution (L)