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