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Entrance exam Hungary > Chemistry > Flashcards

Chemistry Flashcards

1
Q

Structure of an atom

A
  • The atom is up of electrons, protons and neurons
  • In the center of the atoms are protons and neutrons found. The number of neutrons and the number of protons are always the same, except when the element is an isotope. Isotopes are atoms that differ from each other by their mass, which means they differ in the number of protons. The more the number of neutrons and protons differ in the molecule, the more the atoms becomes unstable (and it can become radioactive)
  • Outside the atom are the electrons found.
  • Protons are positive, electrons are negative and neutrons are neutral (no charge)
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2
Q

Structure of a molecule

A
  • The three dimensional shape or configuration of a molecule is an important characteristic. This shape is dependent on the preferred spatial orientation of covalent bonds to atoms having two or more bonding partners
  • Bonding configurations are readily predicted by valence-shell electron-pair repulsion theory, commonly referred to as VSEPR
  • It is necessary to draw structural formulas for organic compounds because in most cases a molecular formula does not uniquely represent a single compound. Different compounds having the same molecular formula are called isomers, and the prevalence of organic isomers reflects the extraordinary versatility of carbon in forming strong bonds to itself and to other elements.
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3
Q

Ionic bond

A

Is formed between a metal and a non-metal. It is formed when one atom accepts or donates an electron to another atom. Electronegativity difference up to 1.8 forms ionic bonds. Strong bond

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4
Q

Covanelnt bond

A

It is formed between 2 non-metals. It can be polar or non-polar, depending on the value of the electronegativity of the 2 elements. If the electronegativity of the 2 atoms is the same then it is polar, if there is a difference then it is non-polar. (atoms share valence electrons) Strong bond

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5
Q

Metal bonds

A

Is formed between 2 metals. Strong bond

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6
Q

Hydrogen bonds

A

Forms when H is directly bonden to F, H, N or O. Weak bond

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7
Q

Dipole-dipole interactions

A 
It can be found in all molecules.
Week bond (the weakest of the intermolecular forces)
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8
Q

What is a solution?

A

A solution is a homogeneous mixture of two or more substances. A solution may exist in any phase. Examples of different solutions; acidic, basic, neutral, alkaline (group 1 metal + water), aquarious solution etc.

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9
Q

Ways of determining the molarity (concentration) of a solution

A
  • Weight percent (wt/wt) = (mass of solute / mass of solution) * 102
  • Volume percent (v/v) = (volume of solute / volume of solution) * 102 ; only if both are liquids
  • Mole Fraction (Xsolute) = (moles of solute / moles of solute + moles of solvent)
  • Molality (m) = (moles of solute / kilograms of solvent)
  • Molarity (M) = (moles of solute / liters of solution)
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10
Q

In order for a solute to be soluble in a particular solution, Which 3 things need to be considered

A
  • The intermolecular forces has to be broken in order for new bonds to form
  • They have to overcome the activation energy
  • the solute and solvent can interact through whatever forces are available
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11
Q

Le Chatlier’s Principle says that…

A

when a stress is applied externally to an equilibrium, the equilibrium is disrupted temporarily and will shift in such a way as to undo the stress that had been applied.

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12
Q

Combustion reaction

A

A combustion reaction is when oxygen combines with another compound to form water and carbon dioxide. These reactions are exothermic, meaning they produce heat. An example of this kind of reaction is the burning of napthalene:
C10H8 + 12 O2 —> 10 CO2 + 4 H2O

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13
Q

Synthesis reaction

A

A synthesis reaction is when two or more simple compounds combine to form a more complicated one. These reactions come in the general form of:
A + B —> AB

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14
Q

Decomposition reaction

A

A decomposition reaction is the opposite of a synthesis reaction - a complex molecule breaks down to make simpler ones. These reactions come in the general form:
AB —> A + B
One example of a decomposition reaction is the electrolysis of water to make oxygen and hydrogen gas:
2 H2O —> 2 H2 + O2

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15
Q

Single displacement reaction

A

This is when one element trades places with another element in a compound. These reactions come in the general form of:
A + BC —> AC + B
One example of a single displacement reaction is when magnesium replaces hydrogen in water to make magnesium hydroxide and hydrogen gas:
Mg + 2 H2O —> Mg(OH)2 + H2

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16
Q

Double displacement reaction

A

This is when the anions and cations of two different molecules switch places, forming two entirely different compounds. These reactions are in the general form:
AB + CD —> AD + CB
One example of a double displacement reaction is the reaction of lead (II) nitrate with potassium iodide to form lead (II) iodide and potassium nitrate:
Pb(NO3)2 + 2 KI —> PbI2 + 2 KNO3

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17
Q

Acid Base reaction

A

This is a special kind of double displacement reaction that takes place when an acid and base react with each other. The H+ ion in the acid reacts with the OH- ion in the base, causing the formation of water. Generally, the product of this reaction is some ionic salt and water:
HA + BOH —> H2O + BA
One example of an acid-base reaction is the reaction of hydrobromic acid (HBr) with sodium hydroxide:
HBr + NaOH —> NaBr + H2O

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18
Q

Inorganic constituents

A

They are compounds or molecules that do not contain carbon, however carbon dioxide and carbon monoxide are exceptions due to the fact that they are classed as inorganic

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19
Q

Hydrocarbons

A
  • They are organic compounds which contain only carbon and hydrogen.
  • The 4 classes of hydrocarbons are: alkane, alkene, alkynes and aromatics
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20
Q

Organic compounds containing oxygen and sulphur

A
  • Sulfur is essential for life, 2 of the 20 common amino acids contain oxygen and sulfur components, and the antibiotics penicillin and sulfa drugs both contain sulfur.
  • While sulfur-containing antibiotics save many lives, sulfur mustard is a deadly chemical warfare agent. Fossil fuels, coal, petroleum, and natural gas, which are derived from ancient organisms, necessarily contain organosulfur (oxygen and sulfur) compounds, the removal of which is a major focus of oil refineries.
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21
Q

Carbohydrates

A

-Carbohydrates consists of carbon, hydrogen and oxygen atoms
-The carbohydrates are divided into 4 groups: Monosaccharides, polysaccharides, oligosaccharides and disaccharides
 Monosaccharides: glucose, fructose, galactose
 Polysaccharides: maltose, lactose, sucrose
 Disaccharides: starch, cellulose, glycogen
-Carbohydrates consist of a long carbon chain
-Function in the body: energy source, energy reserve (short time), precursors for a large number of metabolic reactions (e.g. synthesis of nucleic acids)

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22
Q

Amino acids and proteins

A
  • Proteins are biological polymers composed of amino acids . Amino acids, linked together by peptide bonds, form a polypeptide chain. One or more polypeptide chains twisted into a 3-D shape form a protein. Proteins have complex shapes that include various folds, loops, and curves. Folding in proteins happens spontaneously. Chemical bonding between portions of the polypeptide chain aid in holding the protein together and giving it its shape.
  • Different properties of amino acids: Crystalline compounds, high melting points, more soluble in water then in non-polar solvents, exist as zwitterions, amphoteric can work as buffers
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23
Q

Lipids

A
  • They oxidize well, and so a lot of energy can be obtained
  • They provide long time storage (energy storage in animals), they also protect the organs for damage, steroid hormones
  • Negative effects of lipids: increase risk of heart disease, obesity
  • They are made op of long carbon chains
  • They are hydrophobic (repel water)
  • Examples of different lipids: phospholipids, triglycerides (fats and oils), steroids etc.
  • There are 2 different types of fatty acids: Saturated (single C-C bond) and unsaturated (double C=C bond)
  • Triglycerides consists of one glycerol and 3 fatty acids
  • The unsaturated fatty acids are essential, fatty acids the human body cannot produce by itself. These fatty acids play an important role for our health; they take part in the synthesis of a group of lipids called prostaglandins which are involved in the process of lowering the blood pressure they also lowering the LDL cholesterol (low density lipoprotein)
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24
Q

Vitamins (general)

A
  • Micronutrients are needed in relatively small amounts, in general less than 0.005% of the body mass. Examples are vitamins and trace minerals
  • We get vitamins from food, because the human body either does not produce enough of them, or none at all.
  • Vitamins are essential in normal metabolism; insufficient amounts in the diet may cause deficiency diseases.
  • There are fat soluble vitamins and water soluble vitamins.
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25
Q

Fat-soluble vitamins

A
  • Fat-soluble vitamins are stored in the fat tissues of our bodies, as well as the liver. Fat-soluble vitamins are easier to store than water-soluble ones, and can stay in the body as reserves for days, some of them for months.1
  • Fat-soluble vitamins are absorbed through the intestinal tract with the help of fats (lipids). E.g. A, D, E and K
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26
Q

Water-soluble vitamins

A
  • Water-soluble vitamins do not get stored in the body for long - they soon get expelled through urine.
  • Water-soluble vitamins need to be replaced more often than fat-soluble ones..
  • Vitamins C and all the B vitamins are water-soluble.
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27
Q

Describe the atomic theory (Dalton)

A

a) All matter is made up of atoms (tiny particles)
b) All atoms of a given element are alike, but are different from atoms of different elements
c) Compounds are formed when atoms of different elements combine in fix proportions
d) A chemical reaction involves a rearrangement of atoms, not a change in the atoms themselves

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28
Q

What are the Classification of matter:

A

matter can be found in 3 different phases; liquid, gaseous and solid.

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29
Q

Elements

A

only one kind of atoms are present

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30
Q

Compound

A

more than one elements are present

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31
Q

Atomic number

A

the number of protons in the nucleus

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32
Q

Mass numbers/atomic number

A

It is the number of protons and the number of neutrons

33
Q

Isotopes

A

atoms of the same element but with different mass number (different number of neutrons

34
Q

Molar masses

A

it is the mass of a given substance divided by its amount of substance (M=m/n)

35
Q

Quantum numbers:

A

describes the orbitals in which the electrons can be found

36
Q

Atomic orbitals:

A

A wave function for an electron in an atom. The atomic orbital describes a region of space in which there is a high probability of finding the electron. Energy changes within an atom are the result of an electron changing from a wave pattern with one energy to a wave pattern with a different energy (usually accompanied by the absorption or emission of a photon of light).

37
Q

The periodic table:

A

a tabular arrangement of the chemical elements, organized on the basis of their atomic number (number of protons in the nucleus), electron configurations, and recurring chemical properties. Elements are presented in order of increasing atomic number

38
Q

Properties of gases

A 
- assumes the shape and volume of its container 
particles can move past one another
- compressible 
lots of free space between particles
- flows easily 
particles can move past one another
39
Q

Properties of solid

A
  • assumes the shape of the part of the container which it occupies
    particles can move/slide past one another
  • not easily compressible
    little free space between particles
  • flows easily
    particles can move/slide past one another
40
Q

Properties of liquids

A 
- retains a fixed volume and shape 
rigid - particles locked into place
- not easily compressible 
little free space between particles
- does not flow easily 
rigid - particles cannot move/slide past one another
41
Q

Combination Reactions

A

Two or more reactants form one product in a combination reaction. An example of a combination reaction is the formation of sulfur dioxide when sulfur is burned in air:
S (s) + O2 (g) → SO2 (g)

42
Q

Decomposition Reactions

A

In a decomposition reaction, a compound breaks down into two or more substances. Decomposition usually results from electrolysis or heating.
2HgO (s) + heat → 2Hg (l) + O2 (g)

43
Q

Single Displacement Reactions

A

A single displacement reaction is characterized by an atom or ion of a single compound replacing an atom of another element.
Zn (s) + CuSO4 (aq) → Cu (s) + ZnSO4 (aq)
Single displacement reactions are often subdivided into more specific categories (e.g., redox reactions).

44
Q

Double Displacement Reactions

A

Double displacement reactions also may be called metathesis reactions. In this type of reaction, elements from two compounds displace each other to form new compounds. Double displacement reactions may occur when one product is removed from the solution as a gas or precipitate or when two species combine to form a weak electrolyte that remains undissociated in solution.
CaCl2 (aq) + 2 AgNO3 (aq) → Ca(NO3)2 (aq) + 2 AgCl (s)
A neutralization reaction is a specific type of double displacement reaction that occurs when an acid reacts with a base, producing a solution of salt and water.
HCl (aq) + NaOH (aq) → NaCl (aq) + H2O (l)

45
Q

Stoichiometry

A

-Stoichiometry provides information on fundamental constraints = substrate conversion to product and cell mass from substrate.
-Chemical equation provides a balance sheet which allows us to monitor these changes as reactants are transformed into products. The number of an atom must be the same on both sides. EX.
2H2 (g) + O2 (g)  2H2O (l)

46
Q

Catalyst and reaction rate

A

A Catalyst will increase the forward and reverse reaction, without using itself, will decrease activation energy, will not have an effect on KC

47
Q

Entropy

A

a measure of disorder or randomness in a closed system

48
Q

Exothermic

A

refers to the breaking of bonds. Heat is released as the byproduct.

49
Q

Endothermic

A

refers to the breaking of bonds between molecules. Heat is absorbed.

50
Q

State Hess’s law:

A

regardless of the multiple stages or steps of a reaction, the total enthalpy change for the reaction is the sum of all changes.

51
Q

Law of mass action

A

-The law of mass action is universal, applicable under any circumstance. However, for reactions that are complete, the result may not be very useful. We introduce the mass action law by using a general chemical reaction equation in which reactants A and B react to give product C and D.
a A + b B –> c C + d D
-where a, b, c, d are the coefficients for a balanced chemical equation.
-The mass action law states that if the system is at equilibrium at a given temperature, then the following ratio is a constant.
[C]c [D]d
————- = K
[A]a [B]b

52
Q

Acids and bases

A
  • Acids contain proton (H+) ions and bases contain OH
  • The higher the pH value the more OH is found in the solution and so the more basic the solution is. If there are a lot of H+ then the solution is acidic, the more acidic the solution is depend on the amount of H+ and OH found. If the pH is 7 then the solution is neutral due to the fact that the amount of H+ and OH are balanced.
53
Q

Electrode potential

A

is the electromotive force of a cell built of two electrodes

54
Q

Electrochemical cell

A

is a device capable of either generating electrical energy from chemical reactions or facilitating chemical reactions through the introduction of electrical energy. A common example of an electrochemical cell is a standard 1.5-volt “battery”. (Actually a single “Galvanic cell”; a battery properly consists of multiple cells, connected in either parallel or series pattern.)

55
Q

Describe Electrolysis

A

The use of electric current to stimulate a non-spontaneous reaction. Electrolysis can be used to separate a substance into its original components/elements and it was through this process that a number of elements have been discovered and are still produced in today’s industry. In Electrolysis, an electric current it sent through an electrolyte and into solution in order to stimulate the flow of ions necessary to run an otherwise non-spontaneous reaction.

56
Q

Non-metals

A
  • Group 7 are very reactive non-metals, reactivity decrease down the group.
  • They form ionic compounds with metals or covalent compounds with other non-metals
57
Q

Metals

A
  • There are reactive metals, less reactive metals, the structural metals and coinage metals.
  • Physical properties: Good conductors, low densities, grey shiny surfaces
  • Chemical properties: Very reactive, form ionic compounds with non-metals
58
Q

d-Block elements (transition metals)

A

The d-block elements are located between group 2 and 13 of the periodic table. Transition metals are metals with low ionization energies that exhibit often multiple possible oxidation states.

59
Q

Alkanes

A

Alkanes can react with O2 by combustion reaction. It can burn with the presence of excess oxygen to produce CO2 and H2O. Also burn with a supply of O2 producing CO and H2O. And with extremely limited O2 producing C and H2O.

60
Q

Alkyl groups

A

Alkyl groups are saturated hydrocarbons substituents with the general formula CnH2n+1

61
Q

Alkenes

A
  • is an unsaturated hydrocarbon containing at least one carbon–carbon double bond
  • General formula CnH2n
62
Q

Aromatic hydrocarbons

A
  • is a hydrocarbon with alternating double and single bonds between carbon atoms forming rings
  • many of the compounds have a sweet or pleasant odor.
  • The configuration of six carbon atoms in aromatic compounds is known as a benzene ring, after the simplest possible such hydrocarbon, benzene
63
Q

Alkyl halides (Halogenoalkanes)

A
  • a group of chemical compounds derived from alkanes containing one or more halogens. They are a subset of the general class of halocarbons, although the distinction is not often made.
  • Haloalkane or alkyl halides are the compounds which have the general formula ″RX″ where R is an alkyl or substituted alkyl group and X is a halogen (F, Cl, Br, I).
  • haloalkanes which contain chlorine, bromine, and iodine are a threat to the ozone layer, but fluorinated volatile haloalkanes in theory may have activity as greenhouse gases.
64
Q

Alcohols

A
  • Has OH as its functional group
  • Flammable and readily burn when ignited in air
  • Primary alcohols can be oxidized either to aldehydes or to carboxylic acid. Secondary alcohols oxidize to ketone. Tertiary alcohols are resistant to oxidation.
  • When react with inorganic and organic compounds they will form esters
65
Q

Ethers

A
  • are a class of organic compounds that contain an ether group — an oxygen atom connected to two alkyl or aryl groups — of general formula R–O–R’
  • Ethers are common in organic chemistry and pervasive in biochemistry, as they are common linkages in carbohydrates and lignin.
66
Q

Phenols

A
  • are a class of chemical compounds consisting of a hydroxyl group (—OH) bonded directly to an aromatic hydrocarbon group.
  • Although similar to alcohols, phenols have unique properties and are not classified as alcohols (since the hydroxyl group is not bonded to a saturated carbon atom).
67
Q

Aldehydes

A

Have a hydrogen molecule attached to the carbon and oxygen double bond, functional group: CHO-group.Can oxidize because of the hydrogen atom

68
Q

Ketones

A

Do not have the hydrogen attached to the carbon and oxygen double bond, functional group: CO-group. Cannot oxidize

69
Q

Oxidation of primary and secondary alcohols

A
  • Aldehyde and ketones are made by the oxidation of primary and secondary alcohols.
  • Oxidation agent: sodium or potassium dichromate(VI) acidified with dilute sulphuric acid
  • the orange solution containing the dichromate(VI) ions is reduced to a green solution containing chromium(III) ions.
  • You get an aldehyde from primary alcohols and ketone you get from secondary alcohols
70
Q

Carboxylic acids

A
  • Carboxylic acids are obtained from primary alcohols and aldehydes are normally oxidised to carboxylic acids using potassium dichromate(VI) solution in the presence of dilute sulphuric acid. During the reaction, the potassium dichromate(VI) solution turns from orange to green.
  • an organic compound that contains a carboxyl group (C(O)OH). The general formula of a carboxylic acid is R-C(O)OH with R referring to the rest of the (possibly quite large) molecule
71
Q

Amines

A

Contain nitrogen atom with lone pair, and amine is derivatives of ammonia, where one or more hydrogen atoms are replaced by substituent

72
Q

Heterocyclic compounds

A

a cyclic compound that has atoms of at least two different elements as members of its ring(s). Although heterocyclic compounds may be inorganic, most contain at least one carbon. While atoms that are neither carbon nor hydrogen are normally referred to in organic chemistry as heteroatoms, this is usually in comparison to the all-carbon backbone

73
Q

Stereochemistry

A

a sub discipline of chemistry, involves the study of the relative spatial arrangement of atoms that form the structure of molecules and their manipulation. Stereochemistry includes methods for determining and describing these relationships; the effect on the physical or biological properties these relationships impart upon the molecules in question, and the manner in which these relationships influence the reactivity of the molecules in question

74
Q

Optical activity

A

It is the turning of the plane of linearly polarized light about the direction of motion as the light travels through certain materials. It occurs in solutions of chiral molecules such as sucrose (sugar), solids with rotated crystal planes such as quartz, and spin-polarized gases of atoms or molecules. It is used in the sugar industry to measure syrup concentration, in optics to manipulate polarization, in chemistry to characterize substances in solution, and in optical mineralogy to help identify certain minerals in thin sections

75
Q

Monosaccharides:

A

fructose, glucose and glycogen

76
Q

Disaccharides:

A

lactose, maltose and sucrose

77
Q

Oligosaccharides:

A

Fructo-oligosaccharides, Galactooligosaccharides, Mannan oligosaccharides

78
Q

Carboxylic acid derivatives

A

The important classes of organic compounds known as alcohols, phenols, ethers, amines and halides consist of alkyl and/or aryl groups bonded to hydroxyl, alkoxyl, amino and halo substituents respectively. If these same functional groups are attached to an acyl group (RCO–) their properties are substantially changed, and they are designated as carboxylic acid derivatives. Carboxylic acids have a hydroxyl group bonded to an acyl group, and their functional derivatives are prepared by replacement of the hydroxyl group with substituents, such as halo, alkoxyl, amino and acyloxy.

Entrance exam Hungary (3 decks)

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