Semester 2 Exam Year 11 Flashcards
Who created the Periodic table and when?
Dmitri Mendeleev in 1869.
What are columns and rows called in the Periodic table?
Columns – Groups, Rows – Periods
In what order are elements placed in the Periodic table?
Order is based on their atomic number
In a neutral atom, the number of electrons will equal…?
The number of protons
The number of valence electrons is the same within…?
A column
The number of valence electrons increase…?
Left to right within a row
What are elements represented by?
Symbols
What makes up an atom?
It consists of a nucleus made up of protons and neutrons (nucleons) and an electron cloud where electrons are located.
What is the atomic number?
The number of protons.
What is the mass number?
The mass number is how heavy an atom is. It consists of the number of protons and neutrons in the nucleus.
What is the electron configuration?
The number of shells containing electrons and the number of electrons in each shell.
How many electrons can fit in the first shell?
2 electrons.
How many electrons can fit in the second and third shells?
8 electrons.
How many electrons can fit in the fourth shell?
32 electrons.
What are valence electrons?
The valence electrons of an atom are the electrons located in the highest occupied principal energy level.
What are valence electrons responsible for?
Valence electrons are primarily responsible for the chemical properties of elements.
What is the octet rule?
The octet rule states that atoms tend to form compounds in ways that give them eight valence electrons and thus the electron configuration of a noble gas.
What is the exception to the octet rule?
the first noble gas, helium, which only has two valence electrons.
What are the two ways atoms can satisfy the octet rule?
sharing their valence electrons and transferring valence electrons from one atom to another.
Atoms of metals tend to __ all of their valence electrons, which leaves them with an octet from the next lowest principal energy level.
lose
Atoms of nonmetals tend to __ electrons in order to fill their outermost principal energy level with an octet.
gain
Atoms of nonmetals tend to __ electrons in order to fill their outermost principal energy level with an octet.
gain
What is the atomic radius trend?
Atoms from right to left increase in atomic radius. Atoms from top to bottom also increase in atomic radius. This is because the atomic radius generally decreases as you move from left to right across a period (due to increasing nuclear charge) and increases as you move down a group (due to the increasing number of electron shells).
What is the valence trend?
In a period, the number of valence electrons increases as we move from left to right side. However, in a group this periodic trend is constant, that is the number of valence electrons remains the same.
What is the first ionisation energy trend?
First ionisation energy of an element measures the minimum amount of energy needed to remove the single electron from an atom. It increases going up a group and left to right.
What is ionisation energy?
An element’s ionisation energy is a measure of how strongly it holds onto its electrons.
What is the electronegativity trend?
Electronegativity is the ability of an atom in a molecule to attract electrons to itself. Non-metals have the highest values of electronegativity. It increases from left to right in a period and decreases down a group.
What are isotopes?
Isotopes are atoms of an element with the same number of protons but different numbers of neutrons. Different isotopes of the same element have the same chemical properties but different physical properties.
What is the relative atomic mass?
The average mass of its atoms, compared to 1/12 of the mass of a carbon atom.
What is the formula for relative atomic mass?
A(relative) = total mass of atoms / total number of atoms
How do you calculate formula mass?
Adding up the atomic masses of the elements involved.
What is the units for formula mass?
gmol^-1
What is atomic absorption spectrometry?
A technique that is used to determine the concentration of different elements in solution.
How does atomic absorption spectrometry work?
By focusing light of a specific wavelength on atoms and measuring how much light was absorbed.
What is absorbance?
The measurement of light that is absorbed by a substance.
What happens when an electron absorbs energy?
When an atom absorbs energy, electrons may move from a lower energy level to higher one. Once they have reached a higher level, they drop back down to a lower one. When this happens, the atom emits light. Atoms of different elements absorb and emit certain wavelengths.
What is an absorption spectrum?
An absorption spectrum shows what happens when an atom absorbs certain frequencies of light. The dark stripes represent the light that is absorbed.
What is an emission spectrum?
An emission spectrum shows the frequencies of light that are emitted.
What is mass spectrometry?
An analytical technique where ions are sorted on their mass to charge ratio.
How can mass spectrometry be used quantitively?
Determining the concentration of solution
How can mass spectrometry be used qualitatively?
Identifying elements in a solution.
What does a mass spectrometer produce?
A mass spectrum.
What is a mass spectrum?
A chart that shows the composition of a solution. The components are shown in order of mass to charge ratio. The composition is shown as percent abundance.
What are the four steps to how a mass spectrometer work?
- vaporisation
- ionisation
- acceleration and deflection
- detection
What is a pure substance?
Pure substances are substances that have a fixed or constant composition and cannot be separated into other substances by physical means.They can either be elements or compounds.
what are the two types of mixtures?
homogenous and heterogenous.
What is a homogenous mixture?
A mixture that is uniform in composition
What is a heterogenous mixture?
A mixture that is not uniform in composition.
What is sieving?
Involves separating a mixture based on particle size. The material that makes it through is called the negative fraction. The material that does not make it through is called the positive fraction.
What is filtration and evaporation?
Filtration involves separating solid particles from a solution. Evaporation is drying or heating a solution to separate the solute from the solvent.
What is distillation?
Involves separating components based on their boiling points.
What is magnetic separation?
Separation of paramagnetic and diamagnetic materials.
What is a paramagnetic material?
Paramagnetic materials are slightly attracted by a magnetic field
What is a diamagnetic material?
Diamagnetic materials are slightly repelled by a magnetic field
What is gravity separation?
Involves the separation of materials in a mixture that have different mass.
What are chemical bonds?
Chemical bonds are an attraction between atoms, ions or molecules that enables the formation of chemical compounds
How do atoms form chemical bonds?
the arrangement of electrons in the atom and by the stability of the valence electron shell.
What are chemical bonds caused by?
electrostatic attractions that arise because of the sharing or transfer of electrons between participating atoms
What is valency?
a measure of the bonding capacity of an atom.
What is covalent bonding?
a chemical bond that occurs between non-metal atoms. Both non-metal atoms share electrons to fill their valence shell.
What is metallic bonding?
is a chemical bond that occurs between metal atoms.
What is ionic bonding?
a chemical bond that occurs between a metal atom and a non-metal atom. A metal atom loses an electron to a non-metal atom so they both achieve a full valence electron shell.
What is percentage composition?
the percentage by mass of each element in a compound.
What is the formula for percentage composition?
(mass of element or compound)/mass of mixture * 100
What is polarity?
Polarity is where the electrons are placed in a bond.
How does a polar molecule form?
when one of the atoms exerts a stronger attractive force on the electrons in the bond. The electrons get drawn more towards that atom, so that the molecule exhibits a slight charge imbalance.
If the difference is between __ and __ then the bond will be polar.
0.4 and 1.7
If the difference in electronegativities is greater than 1.7 in a bond, then…
The bond will have an ionic character. This means that the electrons will be taken from the less electronegative element and spend all their time orbiting the more electronegative element.
If the difference in electronegativities is smaller than 0.4 in a bond, then…
the bond will be nonpolar covalent. This means that the electrons will be shared equally between the atoms and the bond will not have a polar character.
What is a dipole moment?
a separation of the molecule into a more positive area and a more negative area.
the negative partial charge is located
at the more electronegative element.
The positive partial charge is located
at the less electronegative element.
The polarity of a bond in a molecule depends on
- Asymmetric electron distribution
- Asymmetric geometry
What is asymmetric electron distribution?
The elements involved in a chemical bond must have a large difference in electronegativity to be polar.
What is asymmetric geometry?
The molecule itself must be asymmetrical to be polar.
What is a covalent molecular substance?
a substance that uses covalent bonds to form molecules.
What are properties of a covalent molecular substance?
Non-conductors of electricity, low melting and boiling points, they are usually liquids or gases at room temperature, solids are soft and easy to mould, only polar molecules are soluble in water.
What is a molecule?
two or more atoms connected by chemical bonds
What is a compound?
a substance which is formed by two or more different types of elements which are united chemically in a fixed proportion.
What is a covalent network substance?
a substance in which atoms are covalently bonded in a continuous network structure.
What are properties of covalent network substances?
Non-conductors of electricity, very hard, normally solids at room temperature, high melting, and boiling points, insoluble in everything.
What is nanotechnology?
the study of nanoparticles and structure
What is a hydrocarbon?
a substance that only contains carbon and hydrogen atoms.
What are the 4 types of hydrocarbons?
- Alkanes/Cycloalkanes
- Alkenes/Cycloalkenes
- Alkynes/Cycloalkynes
- Aromatics
What are Alkanes/Cycloalkanes?
Hydrocarbons that only contain single bonds.
What are Alkenes/Cycloalkenes?
Hydrocarbons that only contain at least one double bond.
What are Alkynes/Cycloalkynes?
Hydrocarbons that only contain at least one triple bond.
What are aromatics?
Compounds that contain a benzene ring
What are the groups that can attach to a hydrocarbon chain?
Chloro, bromo, fluoro, iodo.
What is an addition reaction?
a reaction in which an atom or molecule is added to an unsaturated molecule, making a single product by adding a molecule across the double or triple bond of an alkene or alkyne.
What is hydrogenation?
a reaction that occurs when molecular hydrogen is added to an alkene to produce an alkane.
What is halogenation addition reaction?
A reaction that occurs when a halogen is added to an alkyne or alkene to produce an alkane.
What is halogenation substitution reaction?
Halogenation is the replacement of one or more hydrogen atoms in an organic compound by a halogen nad producing a compound of hydrogen and the halogen.
What is a substitution reaction?
a reaction in which one or more atoms replace another atom or group of atoms in a molecule. Alkyl halides are formed by the substitution of a halogen atom for a hydrogen atom.
What is a combustion reaction?
a reaction in which a substance reacts with oxygen gas, producing water and carbon dioxide.
What are fossil fuels?
hydrocarbon-containing materials composed underground from the remains of dead plants and animals and is extracted and burned as fuel.non-renewable resources
What are examples of fossil fuels?
Coal, oil and natural gas.
What are biofuels?
any fuel made from biomass, such as plant or algae or animal waste.considered a renewable energy source since the raw materials can be easily regenerated.
How are metallic substances formed?
Metal atoms form a lattice of positive ions held together by the electrostatic attraction of delocalised electrons flowing between them.
What are physical properties of metallic substances?
- Shiny
- Hard
- Sonorous
- Compact/Rigid shape
- High melting and boiling points
- Conduct heat and electricity
- Malleable and ductile
What are alloys?
substances that enhance the physical properties of a metal because the insertion of irregularly sized particles disrupts the structure.
What are substitution alloys?
alloys where some of the atoms in the metallic crystal of the primary metal are substituted for atoms of the other element.
What are interstitial alloys?
metallic substance with small atoms filling the spaces (interstices) between the larger metal lattice.
How are ionic substances formed?
An ionic compound is a giant structure of ions. The ions have a regular, repeating arrangement called an ionic lattice. The lattice is formed because the ions attract each other and form a regular pattern with oppositely charged ions next to each other.
What are the properties of ionic compounds?
- Hard and brittle
- High melting and boiling points
- Solids at room temperature (unless dissolved)
- Can conduct electricity in solution or as a liquid but not as a solid
- Soluble in water but not in solvents such as petroleum
What is a cation?
Positive charged ion
What is an anion?
Negative charged ion
What is a monatomic ion?
Consists of one atom
What is a polyatomic ion?
Consists of more than one atom
How do you write chemical formulae for ionic compounds?
first identify the cation and write down its symbol and charge. Then, identify the anion and write down its symbol and charge. Finally, combine the two ions to form an electrically neutral compound.
What are chemical reactions?
a process by which reactants are chemically converted into products. Involves breaking bonds and forming new ones.
What is synthesis chemical reactions?
reaction where it produces a larger molecule out of multiple smaller molecules.
What is decompostion chemical reaction?
chemical reaction where it breaks a large molecule into multiple smaller molecules.
What is a single replacement chemical reaction?
chemical reaction where an element is substituted into a molecule for another.
What is a double replacement chemical reaction?
chemical reaction where two reactant ionic compounds exchange ions to form two new product compounds with the same ions.
What is precipitation?
A double replacement reaction that results in the production of an insoluble solid.
What is combustion?
Reaction of a substance with oxygen in the presence of heat to form oxides.
What is oxidation-reduction?
reaction that involves the transfer of electrons from one reactant to the other to form products.
What is hydrolysis?
reaction of a substance with water
What is neutralisation?
reaction of an acid with a base to form a salt.
What is condensation?
reaction that involves the production of a new substance and water
What is a word equation?
chemical equation where everything is written in words
What is a symbol equation?
chemical equation where the reactants and products are written as their ionic or molecular formulae.
What is an ionic equation?
chemical equations that show only ions that participate in a chemical reaction
What is the law of conservation of mass?
During a chemical reaction, atoms cannot be created or destroyed.
What is enthalpy?
the total energy present in the substance. It includes the energy stored in chemical bonds
and kinetic energy of the particles.
What is chemical potential energy?
energy stored in chemical bonds
The chemical potential energy of a bond is high…
for a weak bond
he chemical potential energy of a bond is low…
for a strong bond
