Atoms and Elements + Hydrocarbons Flashcards
What is an atom?
An atom is the smallest unit of matter that still retains the properties of an element.
what are the 3 subatomic particles in an atom?
- The proton
- The neutron
- The electron
What is the positioning of the sub atomic particles of the atom?
The proton and neutron make up the nucleus of the atom where as the negatively charged electrons can be found around the nucleus in an electron cloud.
What determines the mass number?
Number of protons + Number of Neutrons = Mass number
What is the mass of the neutron and proton?
The neutron and proton are ALMOST identical in mass, each about 1.7 × 10^-24 gram (g)
What unit of measurement is used to measure atoms and subatomic particles (and for molecules too) ?
We use a unit of measurement called dalton for atoms and subatomic particles (and for molecules too.)
What is the dalton the same as?
The dalton is the same as the atomic mass unit, or (amu)
What is the mass of the neutron and proton in dalton?
Neutrons and protons have masses close to 1 dalton.
Because the mass of an electron is only about 1/2000 that of a neutron or proton we can ignore electrons when atomic mass.
Different models of atom?
- Planetary model or Bohr model ( 1913)
- Electron cloud model Schrodinger (1926)
What is an element?
Any substance that cannot be broken down to any other substance by chemical reactions.
What is the atomic number and atomic mass number?
The atomic number is the sum of the protons and is located at the top of the element.
The atomic mass is the sum of the protons and neutrons and is located at the bottom of the element.
How do you know the number of electrons?
In an uncharged atom, the number of protons is always the number of electrons
What is a compound?
A compound is a substance consisting of 2 or more different elements combined in a fixed ratio
E.g. Na + Cl = NaCl (Sodium Chloride)
What are isotopes?
Isotopes are atoms with the same number of protons but a different number of neutrons
All the atoms of an element would have the same number or protons but some have more neutrons than other atoms of the same element this therefore gives it a greater mass.
If isotopes have slightly different masses does that change how they behave in chemical reactions?
Although the isotopes of an element have slightly different masses, they behave identically in chemical reactions.
What are 12 C and 13C
12C and 13C are both stable isotopes meaning their nuclei do not have a tendency to lose subatomic particles, a process called decay.
What is the 14C isotope?
The 14C isotope is unstable, or reactive
What is a radioactive isotope?
A radioactive isotope is one in which the nucleus decays spontaneously, giving off particles and energy.
When the radioactive decay leads to a change in the number of protons, it transforms the atom to an atom of a different element.
With isotopes what happens to the atomic mass?
The atomic mass of some elements is not always an integer (i.e. not a whole number)
The atomic mass is an average of the different isotopes of the element.
What is radioactive decay?
Radioactive decay is the process in which a radioactive atom spontaneously gives off radiation in the form of energy or particles to reach a more stable state.
What is alpha decay?
In alpha decay, the nucleus loses 2 protons
What is beta decay?
In beta decay, the nucleus either loses or gains a proton
What is gamma decay?
In gamma decay, no change in proton number occurs so the atom does not become a different element.
What is valence?
Valence is the bonding capacity of a given atom, the number of covalent bonds that an atom can form which usually equals the number of unpaired electrons in the outermost (valence) shell.
What is valence electron?
A valence electron is an electron in the outermost electron shell.
What is a valence shell?
A valence shell is the outermost shell of an atom, containing the valence electrons involved in the chemical reactions of that atom
What is an electrons energy level correlated with?
Its average distance from the nucleus.
What determines the chemical behaviour of an atom?
The chemical behaviour of an atom depends mostly on the number of electrons in its outermost shell.
What is a covalent bond?
A type of strong chemical bond in which 2 atoms share one or more pairs of valence electrons
What is electronegativity?
Electronegativity is the attraction of a given atom for the electrons of a covalent bond.
What is a non polar covalent bond?
A non polar covalent bond is a type of covalent bond in which electrons are shared equally between two atoms of similar electronegativity.
What is a polar covalent bond?
A polar covalent bond is a covalent bond between atoms that differ in electronegativity. The shared electrons are pulled closer to the more electronegative atom, making it slightly negative and the other atom slightly positive.
What is an ion?
An atom or group of atoms that has gained or lost one or more electrons, thus acquiring a charge.
What is a cation?
A positively charged ion
What is anion?
A negatively charged ion
What is an ionic bond?
A chemical bond resulting from the attraction between oppositely charged ions.
What is a hydrogen bond?
A hydrogen bond is a type of weak chemical bond that is formed when the slightly positive hydrogen atom of a polar covalent bond in one molecules is attracted to the slightly negative atom of a polar covalent bond in another molecule or in another region of the same molecule.
What are the Van der Waals interaction?
The Van der Waals interaction are dipole - dipole interactions which commonly exist in gases, liquids and solids.
What are the 3 types of Van der Waals forces
1) Dipole - dipole interactions
2) Dipole - induced dipole interactions
3) London dispersion forces
The strongest type of Van der Waals interaction are dipole - dipole interactions.
How is carbon present in our daily life?
Carbon is present in our daily lives:
- Present in virtually all molecules in the body: fats, sugars, DNA and proteins
- Source of energy
- Carbon cycle e.g. plants recycle it from CO2
- Allows variety and complexity of molecules
- Organic if it contains carbon
What was the black earth?
Time period many years ago where there was high temperature high pressure and toxic gases.
Who were the scientists that experimented on the origin of life on earth from simple compounds?
Harold Urey and Stanley Miller
What are abiotic factors?
Non living part of an ecosystem
What did Stanley Miller and Harold Urey experiment find out?
That we can generate amino acids.
What is the structure of proteins?
- Primary Structure
- Secondary structure
- Tertiary structure
- Quaternary structure
Carbon is required to build amino acids and proteins.
How much does carbon make of the body and what different molecules contain carbon?
a) 18%
b) Hexane, Glucose, Fructose, Glycerol, DNA
What is the octet rule?
The tendency of atoms to prefer to have 8 electrons in the valence shell. (Basically in order for an atom to be stable it needs 8 electrons in the outer shell)
What are hydrocarbons?
They are composed of hydrogen and carbon
What are hydrocarbons constituents of? (part of)
Fossil Fuels
Plastics
Drugs
Plants etc
Different Hydreocarbons?
- Gases (methane, propane)
- Liquids (benzene)
- Solids (paraffin wax, naphthalene)
- Polymers (polyethylene and polystyrene)
Classification of Hydrocarbons?
Hydrocarbons
Aliphatic Aromatic
- Conjugated
system of single and
double bonds - usually in a
ring
- e.g. benzene
Saturated OR Unsaturated
-all bonds are a single bonds Have double or triple bonds
-linear or ring Linear or ring
-Alkanes ( - C - C -) Alkenes (-C=C)
Alkynes (-C≡C-)
What does Aliphatic mean?
They are generated from the chemical degradation of oils
What does Aromatic mean?
They are generated from the chemical degradation of plants
What are alkanes?
- Alkanes are the simplest class of hydrocarbons
- Each carbon bonded to 4 other atoms
- When naming the suffix ‘ane’ is used
- General formula of CnH2n+2
What do all alkanes have?
- Same general formula
- Similar chemical properties
-Gradual variation in physical properties
How do you get from an alkane to an alkyl?
Alkanes - Alkyl
Minus a Hydrogen
e.g. CH4 = Methane CH3 = Methyl
Simple Alkanes?
1 Carbon = Methane
2 = Ethane
3 = Propane
4 = Butane
5 = Pentane
6 = Hexane
7 =Heptane
8 = Octane
9 = Nonane
10 = Decane
How to name simple alkanes with substituents (Alkyl groups)
1) Find the longest continuous carbon chain (parent chain)
2) Identify the type of substituent attached to the parent chain
3) Number the carbon chain so we have the most substituents ( side chain) and lowest number at each substituent
4) Write the full name as: number (position of substituent) - substituent name (for each group in alphabetical order) parent name
REVISE USING LEC CAPTURE HOW TO DO THE IUPAC
What do alkanes only contain?
C - C single bonds
What do alkenes contain?
At least one C = C double bond
What do Alkynes contain?
At least one C ≡ C triple bond
What are hydrocarbon functional groups?
- They display consistent function
- Affect structure, solubility and reactivity
- Chemical motifs or pattern of atoms
- Part of hydrocarbon framework via covalent bonds
7 Functional groups
1 ) Hydroxyl group (OH) e.g. Alcohols
2) Carboxyl groups (COOH) e.g. amino acids
3) Carbonyl group ( C=O) e.g. Ketone/ aldehydes
4) Amino group (NH2) e.g. Amino acids
5) Sulfhydryl groups (SH) e.g. protein structure
6) Phosphate group (OPO3^2-) e.g. DNA
7) Methyl group (CH3) e.g. DNA methylationA
Amino acids?
Both carboxyl and amine group. They also have a side chain (R group)
Amino acids act as buffers
What happens when 2 SH groups cross link?
When 2 SH groups cross link it stabilises the protein structure
Phosphate group?
- Charged
- Acidic: release H+ ions into solutions
e.g. sugar phosphate backbone of DNA
Methy group?
From methane
Hydrophobic and non polar
What is DNA methylation?
Change activity of DNA segment without changing the sequence
Methylation affects gene expression
What are isomers?
Same molecular formula different arrangement of atoms
- Different structure and properties
- Equal number of atoms of the same element
What is chain isomerism?
Different arrangement of chain backbone
Consider the molecular formula of C6 H14
What is position isomerism
Different position of functional group within chain
Consider the molecular formula C3H8O
What is Functional group isomerism?
Different functional groups
Consider the molecular formula of C4H8O2W
What are cis - trans isomers?
- Equal number of C and H atoms
- Inflexibility of double bond - restricted rotation
- Different orientations across a double bond
- Different spatial arrangements
What are conformational isomers?
- Different orientations of a ring structure
- Rotation around a single bond
- Interconvert
What are Enantiomers?
- Optically active
- Racemic mixture (equal amount of D and L isomers)
