Foundations In Chemistry Flashcards
What is the charge of a proton
1+
What is the charge of an electron
1-
Which particle has the same mass as a proton
Neutron
Which two particles make up most of an atoms mass
Protons and neutrons
Which letter is used to represent the atomic number of an atom
Z
What does the atomic number tell us
The number of protons
Which letter represents the mass number
A
How to calculate the number of neutrons
Mass number- atomic number
Define isotope
Same protons different neutrons
What are ions
Charged particles formed when an atom loses/gains electrons
Define relative atomic mass
The weighted mean mass of an atom of an element compared with one twelfth of the mass of an atom of carbon-12
Define relative isotopic mass
The mass of an atom of an isotope compared with one twelfth of the mass of an atom of carbon-12
What two assumptions are made when calculating mass number
Contribution of electron is ignored and the mass of both proton and neutron is taken as 1.0u
How to calculate relative molecular mass and relative formula mass
Add relative atomic masses of each atom making up the molecule or the formula
3 uses of mass spectroscopy
Identify unknown compounds
Find relative abundance of each isotope
Determine structural information
How does a mass spectrometer work
Sample made into positive ions
Pass through Apparatus and separated according to mass to charge ratio
A computer analyses the data and produces mass spectrum
Do metals usually gain or lose electrons
Lose electrons
What are molecular ions
Covalently bonded atoms that lose or gain electrons
Charge of an ammonium ion
+1
Charge of a hydroxide ion
-1
Charge of a hydroxide ion
-1
Charge of a nitrate ion
-1
Carbonate ion
-2
Sulfate ion
-2
Empirical formula
Simplest whole number ratio
Calculate empirical formula
Divide amount by molar mass
Divide by smallest number
If decimal decide by suitable number to make whole
Symbol for amount of substance
n
Unit to measure amount of substance
Mole
What does avogadro constant represent
Number of atoms per mole of carbon-12 isotope
Calculate mass of 1 mole of an element
Relative atomic mass in grams
Mole equation
Moles=mass/ molar mass
Avogadros law
Under the same temperature and pressure one mole of any gas would occupy the same volume
How much volume does a gas occupy at room temperature and pressure
24dm^3
Define molar gas volume
Volume per mole of gas molecules
Why do different gas particles occupy the same volume
Gas particles are very spread out so individuals differences have no effect
Moles when gas volume is given
Moles=volume(dm^3)/24
Moles=volume(cm^3)/24000
Ideal gas equation
Pressure(Pa)×volume(m^3) =moles×gas constant(8.314)×temperature(k)
0°c = how many kelvin
273
What does concentration of a solution mean
Amount of solute dissolved in 1dm^3 of solvent
Moles when given concentration and volume
Moles=conc×vol
What is a standard solution?
A solution of a known concentration
Steps to prepare a standard solution
Weigh solution
Dissolve solute using solvent
Pour into volumetric flask
Rinse beaker using solution and add it to flask
Add solvent until it reaches graduation line
Mix thoroughly
…..
….
What does percentage yield mean
Efficiency reactants are converted into products
How is percentage yeild calculated
Percentage yeild=actual amount of product/ theoretical amount×100
What does atom economy mean
The proportion of desired products compared with all the products formed in the reaction
How is atom economy calculated
Atom economy= Mr desired product/ sum of Mr of all products×100
When an acid is added to water what in is released into solution
H+
Define acid
Proton donor
Describe the dissociation of a strong acid
Full disassociation
Define base
Proton acceptor
Which base is used to treat acid indigestion
Magnesium hydroxide
What are alkalis
Bases that can dissolve in water to form aqueous hydroxide ion
What are amphoteric substances
Substances that can act as acids and bases
What is formed when acids react with carbonates
Salt carbon dioxide and water
What is a salt
A compound formed when h+ of an ion is replaced by a metal ion or positive ion
What if formed when acids react with metal oxides
Salt and water
Formed when acids reacts with alkali
Salt and water
Formed when acids react with metal
Salt and hydrogen
How are ammonium salts formed
When an acids reacts with aqueous ammonia
What are hydrated crystals
A crystalline structure containing water
What does anhydrous crystals mean
Crystalline form that contains no water
What does a dot formula indicate
The amount of water in a crystalline structure
Method to carry out titration
Measure out the volume of a solution using a pipette
Add into a conical flask and add indicator
Add the other solution into a burette
Slowly add the burette solution into the conical flask
Swirl the mixture
Repeat until concordant results are obtained
What is an oxidation number
The number of electrons an atom uses to bond with any other atom
What is the oxidation number of an uncombined element
0
Oxidation number of oxygen
-2
Oxidation number of oxygen in peroxides
-1
Oxidation number hydrogen
+1
Oxidation number hydrogen( metal hydrides)
-1
Oxidation number simple ion
The charge of the ion
Oxidation number flourine
-1
What are oxyanions
Negative ions that have an element along with oxygen
Define oxidation
Loss of electrons
An increase in oxidation number
Define reduction
Gain of electrons
A decrease in oxidation number
What is a redox reaction
A reaction in which both oxidation and reduction takes place
What does the principal quantum number indicate
The shell occupied by the electrons
What is a shell
A group of orbitals with the same principal quantum number
How many electrons can the 1st shell hold
2
How many electron can the 2nd shell hold
8
What is an orbital
A region around the nucleus that can hold up to two electrons with opposite spins
When using electrons in box representation what shape is used to represent the electrons
Arrows
Why does 4s orbital fill before 3d orbital
4s orbital has a lower energy than 3d before it is filled
Which electrons are lost when an atom becomes a positive ion
Electrons in the highest energy levels
What are the three main types of chemical bonds
Ionic covalent metallic
Define ionic bonding
The electrostatic attraction between positive and negative ions
Define covalent bonding
Electrostatic attraction between a shared pair of electrons and the nuclei
Define metallic bonding
Electrostatic attraction between the positive metal ions and the sea of delocalised electrons
Electrons in which shell are represented in a dot and cross diagram
The outer shell
Why does giant ionic lattices conduct electricity when liquid but not when solid
When solid the ions are fixed and cannot move when the are liquid they are free to move and carry a charge
Giant ionic lattices have high or low melting and boiling point
High- a large amount of energy is required to overcome the electrostatic bonds
In what type of solvents do ionic lattices dissolve
Polar solvents
What is a lone pair
Electrons in the outer shell that are not involved in the bonding
What is a dative covalent bond
A bond where both of the shared electrons are supplied by one atom
Describe the bonding in simple molecular structures
Atoms within the same molecule are held by strong covalent bonds and different molecules are held together by weak intermolecular forces
Why do simple molecular structures have low melting and boiling points?
Small amount of energy is enough to overcome the intermolecular forces
Can simple molecular structures conduct electricity
No
Properties of giant covalent structures
High melting and boiling points
Non conducters of electricity
Insoluble in polar and non polar solvents
What is the shape and bond angle- 2 bonded pairs and 0 lone pairs
Linear 180°
3 bonded pairs 0 lone pairs
Trigonal planar 120°
4bonded pairs 0 lone pairs
Tetrahedral 109.5°
5 bonded pairs 0 lone pairs
Trigonal bipyramid 90° and 120°
6 bonded pairs and 0 lone pairs
Octahedral 90°
3 bonded pairs 1 lone pair
Pyramidal 107°
2 bonded pairs 2 lone pairs
Non linear 104.5°
Define electronegativity
The ability of an atom to attract the pair of electrons in a covalent bond
What are the two types of intermolecular forces
Hydrogen bonding
Van der waal’s forces
What are the 2 interactions that can be referred to as van der waal’s forces
Induced dipole-permanent dipole
Permanent dipole- permanent dipole
Describe London forces
London forces are caused by random movements of electrons
Leads to instantaneous dipoles
These induce a dipole in nearby molecules
These attract each other
Does boiling point increase or decrease down the noble gas group
Increases no. Electrons increases hence the strength of London forces also increases
