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Pre-med chemistry > Chemistry basics > Flashcards

Chemistry basics Flashcards

1
Q

What is Chemistry, particles and matter?

A

Chemistry = The study of matter. Particles = Particular types of matter. Matter = everything the universe is made of.

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2
Q

What is a chemical reaction?

A

Chemical reaction = a process in which particles interact to form new particles with different compositions.

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3
Q

What is an element?

A

A single substance that cannot be split by chemical means into something simpler.

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4
Q

What is an atom?

A

The smallest particle into which an element can be divided whilst retaining its properties.

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5
Q

What are the subatomic particles?

A

Protons (+1), neutrons (0) and electrons (-1).

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6
Q

What is the significance of electrons?

A

They = the no. protons in the nucleus - determine chemical reactivity. Circle nucleus at speed of light, staying in energy levels.

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7
Q

What is the proton number and has number?

A

Atomic number = no. protons. Mass number = no. protons + neutrons.

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8
Q

What are chemical and physical properties?

A

Chemical = trait of a substance that can be observed when it participates in a chemical reaction. Physical = trait that can be observed or measured without changing the chemical composition of the substance.

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9
Q

What are the periods and groups?

A

Period = horizontal row of elements. Trends in chemical + physical properties across the period.
Group = vertical column of elements. They share similar chemical + physical properties.

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10
Q

What are metals?

A

Metal = Shiny, malleable elements that are good thermal and electrical conductors, are solid at room temp. and form positive ions.

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11
Q

What are non-metals?

A

Poor thermal and electrical conductors. Form negative ions.

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12
Q

What are metalloids?

A

They have the appearance of a metal but the chemical properties of a non-metal.

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13
Q

What are the four sub-shells?

A

S block (alkali + alkaline-earth metals), P block (metals + non-metals + metalloids), D block (transition metas), F block (lanthanides + actinides).

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14
Q

What are atomic orbitals?

A

Particular region of space around the nucleus with a high likelihood of finding an electron.

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15
Q

What are the shapes of the S,P,D and F orbitals?

A

S = spherical, P = figure of 8, D = four-leaf clover, F = Tetrahedral.

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16
Q

Each sub-shell fits how many orbitals?

A

S = 1, P = 3, D = 5, F = 7.

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17
Q

What is a chemical equation?

A

Symbolic representation of a chemical reaction in the form of symbols and chemical formulas.

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18
Q

What is an ionic equation?

A

a chemical equation that shows the reacting ions of an aqueous solution.

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19
Q

What is a chemical bond?

A

electrostatic forces of attraction between two or more atoms to become stable.

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20
Q

What are ionic bonds?

A

(Metals + non-metals) electrostatic forces of attraction between positive and negative ions.

21
Q

What are covalent bonds?

A

(Two non-metals) electrostatic forces of attraction between shared electron and bonded nuclei.

22
Q

What are metallic bonds?

A

Electrostatic forces of attraction between metal positive ions and a sea of delocalised electrons.

23
Q

What is electronegativity?

A

The ability of an atom to attract the bonding electrons to itself.

24
Q

What types of ionic and covalent bonds are there?

A

Pure covalent = Totally equal sharing of electrons. Polarised covalent = electrons shared unequally.
Pure ionic = electrons transferred completely. Ionic with covalent character = electrons transferred, but ions polarised.

25
Q

What are intermolecular forces?

A

Electrostatic forces of attraction between the molecules of a substance.

26
Q

What are London Forces?

A

Electron clouds wobble on one atom to produce a temporary dipole. (Positive nucleus) Temporary dipole pulls electron clouds on a neighbouring atom causing an induced dipole.

27
Q

What are dipole-dipole bonds?

A

Partial charges in 1 molecule attracted to opposite partial charges in a nearby molecule.

28
Q

What are hydrogen bonds?

A

Type of dipole-dipole bond resulting from an electropositive hydrogen atom covalently bonded to an electronegative atom being attracted to anther electronegative atom.

29
Q

What is atomic radius?

A

A measure of the typical distance from the nucleus’ centre to the outermost electron.

30
Q

What are the trend for atomic radius across the period?

A

Period = atomic radius (drop) due to nuclear charge (up) - protons (up) in nucleus + electrons (up) in energy levels so electrostatic forces size (up) so electrons pulled closer to the nucleus.

31
Q

What is the trend for atomic radius down the group?

A

group = atomic radius (up) due to no. energy levels occupied (up) + size of orbitals (up) so outweigh (up) in nuclear charge.

32
Q

What is First Ionisation energy?

A

The energy required to remove 1 electron from 1 mole of gaseous atoms to form 1 mole of gaseous ions.

33
Q

What are the factors that determine first ionisation energies?

A

Nuclear charge - protons in nucleus (up) = nucleus + outer electron attraction (up).
Atomic radius - nucleus + outer electron distance (up) =electrostatic forces (drop).
Electron shielding - electrons are negative so inner electrons repel outer electrons.
Trends = FI energy (drop)

34
Q

What is the trend in the group 1 alkali metals for the reaction with water?

A

Trend = faster chemical reactions because activation energies (drop) due to an energy decrease for metals to lose an electron.

35
Q

What is electron affinity?

A

The energy released when 1 mole of gaseous atoms each acquire an electron to form 1 mole of gaseous ions.

36
Q

What is the trend for electron affinity across the period and down the group?

A

Period = smaller atomic radius so nucleus + electron distance (drop) so electrostatic forces (up).
group = (up) in atomic radius so nucleus + electron distance (up) so electrostatic forces (drop).

37
Q

What types of chemical reactions are there?

A

(Redox) Oxidant + reductant = oxidised reductant + reduced oxidant.
(acid-base) - acid + base = salt + water.
(Single replacement) AB + C = AC + B.
(double replacement) AB + CD = AD + CB.
(Synthesis) A + B = AB.
(decomposition) AB = A + B.

38
Q

Redox vs acid-base reactions?

A

(Redox) - electron transfer + oxidation/reduction reactions + common among transition metals + always an oxidation no. change.
(acid-base) - proton transfer + neutralisation reaction + acids and bases + no oxidation no. change.

39
Q

What is the reducing agent and the oxidising agent?

A

(Reducing agent) causes reduction + undergoes oxidation so loses electrons.
(Oxidising agent) causes oxidation + undergoes reduction so gains electron.

40
Q

What is a precipitation reaction?

A

The chemical reaction in an aqueous solution that produced an insoluble solid.

41
Q

What is a chemical system + an enthalpy change?

A

Chemical System = The molecules, atoms or ions making up the chemicals.
Enthalpy change = thermal energy change in a chemical system (stored in bonds).

42
Q

What is an exothermic and an endothermic reaction?

A

(Exothermic) Chemical system energy transferred to surroundings + temp. of surroundings (up).
(Endothermic) Surroundings energy taken up by chemical system + temp. of surroundings (drop).

43
Q

What is the measurement of an enthalpy change?

A

Enthalpy change = enthalpy of products - enthalpy of reactants (KJ per mole).

44
Q

What is a standard enthalpy?

A

The enthalpy change of a chemical reaction under standard conditions (Temp. = 25 degrees celsius + 100 kPa + 1 mole per dm cubed + typical states).

45
Q

What is the standard enthalpy of formation?

A

The enthalpy change when 1 mole fo a compound is formed from its elements under standard conditions.

46
Q

What is entropy?

A

Entropy (up) = energy ability to do work (drop) so system (up) disordered.
A measure of the dispersion of energy in a chemical system (J per K per mol).
Positive always but positive + negative changes.
Equation entropy change - compare physical states on each side.

47
Q

What is the Free energy change of a chemical reaction?

A

The total energy change of a chemical reaction, taking into account the entropy change + the enthalpy change.

48
Q

What is The Gibbs’ equation?

A

G (change) = H (change) - T x S (change). The free energy change must be negative for a chemical reaction to be feasible.

Pre-med chemistry (4 decks)

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