chemistry exam revision Flashcards
what is an atomic number?
the number of protons in an element and also the number of electrons in a neutral atom of an element.
what is an atomic mass (mass number)
the number of protons + neutrons in an isotope of an element
what 3 things need to happen for a reaction to occur? ( collision theory)
- particles must collide
- particles must have enough energy
- particles must hit at correct orientation
what factors increase the reaction rate?
- increasing temp
- increasing concentration of reactants
- increasing the surface area
- adding a catalyst
which has a higher surface area? a whole tablet or a crushed tablet
crushed tablet
How does increasing the temperature increase the reaction rate?
Increasing the temperature provides particles will kinetic energy. This makes particles move more/faster and collide more frequently.
How does increasing the concentration increase the reaction rate?
The more concentrated a substance the more particles there are in the same volume of space.-This clumps the particles together closer, leading more more frequent collisions.
How does increasing the surface area increase the reaction rate?
Increasing the surface area, increases the number of particles exposed to the reactants.More particles, leads to more frequent collisions.
How does a catalyst increase reaction rate?
-catalyst is not involved in the reaction-A catalyst decreases the activation energy/energy require for a reaction to occur.
On the periodic table, which number is the atomic number? big or small.
small
On the periodic table, what is the large number referred to as?On the periodic table, what is the large number referred to as?
atomic mass
The atomic number indicates the number of what in an atom?
protons
The atomic mass indicates the number of what in an atom?
the SUM of protons and neutrons in the atom
What 3 things make up an atom?
protons, neutrons and electron
what charge are electrons?
negative
What charge are neurtons?
neutral
what particles are in the atom’s nucleus?
protons and neutrons
How many electrons can be in each electron shell?
1st= max 2
2nd = max 8
3rd= max 8
4th = max 18
what is a valance electron?
The electrons that are in the outermost shell
How can the periodic table tell us the number of valence electrons an atom has?
the period groups.
group 4= 4 valence electrons
group 13= 3 valence electrons
Which side of the period table are most metals located
middle and left hand side
what side of the periodic table are most non-mentals found
the right hand side
what is the name given to group 1 metals?
Alkali mentals
what is the name given to group 2 metals?
Alkaline metals
what is the name given to group 17 metals?
halogen
what is the name given to group 18 mentals
Nobel gases
What is an isotope?
A variation of the same atom with different numbers of neutrons
The atomic size of atoms increases in what direction across the periodic table?
-From right to left
- & from top to bottom
The reactivity of metals increases as you go…
up or down the periodic table?
down
BOTH
Why does the atomic size of atoms increase as you more left across and down the periodic table?
Because the number of charged particles in the nucleus decreases (protons). This creates less electrostatic attraction between protons and the electrons. This means that electrons will NOT get pulled closer to the nucleus, but rather stay further away. This creates a larger atomic size.
BOTH
Why does the reactivity of metals increase as you move down the periodic table?
Because there is less electrostatic attraction between the protons and the electrons. Therefore, the electrons are more easily pulled away from the atom to react.
The reactivity of metals increases as you go…left or right across the periodic table?
from right to the left
Are the reactivity trends of non-metals the same or opposite to metals?
opposite
What is an ion?
A charged atom.
An atoms that has lost or gained electrons
If an atom loses an electron will it be positively or negatively charged?
positive
If an atom gains an electron will it be positively or negatively charged?
negatively
If an atom gains 3 electrons what will its valence/charge be?
3-
The periods that run across the periodic table tell you what about an atom?
The number of orbital energies it has.
Lithium is in period 2 and will have 2 shells of electrons.
What are some characteristics of alkali metals?
-VERY soft
-VERY reactive
-have 1 valence electron
What are some characteristics of alkine metals?
-soft
-reactive
-have 2 valence electron
What are some characteristics of metalloids?
have characteristics of metals and non-metals
What type of elements are involved in metallic bonding?
metals only
What type of elements are involved in ionic bonding?
metals and non- metals
What type of elements are involved in covalent bonding?
non-metals only
What are some characteristics of metallic substances?
shiny/lustrous
-malleable
-good conductors of heat and electricity
-ductile
- high melting point
What are some characteristics of ionic substances?
-very brittle (form a lattice)
-bad conductors in solid state
-good conductors in aqueous state
-strong
-high melting point
What are some characteristics of covalent substances?
-bad conductors
-good insulators
-brittle
-low boiling point
Why are metals good conductors?
-because they have free floating delocalised electrons that are charged and can carry heat or an electrical current through them easily.
Why are ionic substances brittle?
Because they are in the form of a lattice.
-When they are hit/impacted it will cause two like charges to align.
-when 2 like charges align they will repel each other and break the substance/lattice.
Why are ionic substances conductors in an aqueous solution and not as a solid?
because as a solid all the particles are locked into a lattice. Therefore, there are not free moving charged particles available to carry heat or a current.
-When in an aqueous solution the ionic substance dissociates into ions. These ions have charges. These charged particles are free to move and carry heat or a current.
Why are ionic substances conductors in an aqueous solution and not as a solid?
because as a solid all the particles are locked into a lattice. Therefore, there are not free moving charged particles available to carry heat or a current.
-When in an aqueous solution the ionic substance dissociates into ions. These ions have charges. These charged particles are free to move and carry heat or a current.
What happens to electrons in ionic bonding?
-they are transferred.
-the metal loses electrons
-the non-metal gains electrons
What happens to electrons in covalent bonding?
-the non-metals share electrons
What happens to electrons in metallic bonding?
-the metals shared electrons in a sea of delocalized electrons
Are brackets needed when writing chemical/ionic formula with NO polyatomic molecules?
no
Are brackets needed when writing chemical/ionic formula with ONE polyatomic molecules?
no
what is a subscript
a small number on the bottom right of an element
what does a subscript tell us
how many of those atoms are in the compound/molecule/element
what is a coefficient
A large number at the front of a compound/molecule/element that indicates how many of that compound/molecule/element there are.
Is chloride a polyatomic atom?
no
Is nitrate a polyatomic atom?
yes
Is hydroxide a polyatomic atom?
yes
Is Aluminium a polyatomic atom?
no
Is phosphate a polyatomic atom?
yes
If an element is not in a compound/molecule, how do you write it’s chemical formula?
-Just write the element.
Calcium = Ca
What are diatomic elements?
-elements that naturally exist in pairs.
What elements are diatomic?
oxygen
fluorine
nitrogen
hydrogen
chlorine
How many electrons do atoms want to be stable?
8
when naming compounds… what three letters do you end in?
“ide”
If naming an ionic compound, do you need to write prefix (mono,di, tri)?
no
if naming a covalent compound, do you need to write prefix (mono,di,tri)?
yes
If you have only 1 of the first element in a covalent compound.. do you need to write mono?
no
What are reactants?
substances that start a reaction
What are products?
substances that are produced from a reaction
What is the law of conservation of matter?
matter cannot be created or destroyed
What is the chemical formula for hydrochloric acid?
HCI
What is the chemical formula for sulfuric acid?
H2SO4
What is the chemical formula for Phosphoric acid?
H3PO4
What is the chemical formula for Nitric acid?
NHO3
In a precipitation reaction/ionic reaction. Do you write all the compounds present or only the ions that make the precipitate?
only the ions that make the precipitate
What is a precipitate?
an insoluble solid that is formed when two solutions are mixed?
what does soluble mean?
A substance can dissolve
what does insoluble mean?
a substance that cannot dissolve
what is solute
the substance that is dissolving.
Eg. salt.
Salt dissolves in water
what is solvent?
the substance that something dissolves in.
Eg. water
water dissolves salt
what does concentrated mean?
There are lots of particles within the volume of space.
what does dilute mean?
there are very few particles within the volume of space.
When writing the chemical/ionic formula for a substance… what is the aim?
balancing the charges and cancelling them out!
What symbol is used to show a chemical reaction in an equation?
an arrow
BOTH
Count the atoms in the following atoms:
C6H12O6
Carbon= 6
Hydrogen= 12
Oxygen =6
How do you show an aqueous solution in an equation?
(aq)
How can you identify the precipitate in a reaction?
Identify the insoluble product from the reaction using the solubility table
In a precipitation reaction between substance AB and substance CD, what are the products?
AD and CB
Do you look for a precipitate in the reactants or the products of an equation.
products only !
In an ionic dot diagram, do you need to draw brackets?
yes
In a covalent dot diagram, do you need to draw brackets?
no
In ionic and covalent dot diagrams do you need to draw all electrons or just the valence electrons?
just the valance electrons
If an atom has a charge of 3+, how many electrons has it gained or lost?
lost 3
