atoms and the periodic table Flashcards
what do the rows tell you in the periodic table?
elements in the same row have the same number of occupied elctron shells
what do groups tell you
elements in the same group have the same number of electrons in their outer shells
how are the elements arranged in the modern periodic table?
they are arranged by atomic number
who first organised the periodic table?
john newlands
how did john newlands first organize and what did he notice about the periodic table?
he ordered them using the atomic masses and he noticed a pattern which he called octaves where each element was similar to the one eight places ahead of it
what were the problems with john newlands table?
many of his atomic weights were not accurate
he sometimes would put two elements in the same box when convienient
some elements in an octave had very different properties
no spaces for undiscovered elements
who ordered the table after john newlands more succesfully?
dmitri mendeleev
how did dmitri mendeleev organize the periodic table?
organized them by the atomic weights and properties
why was dmitri menedleev table so much better than john newlands/
he recallculated the atomic weights
he left gaps for undiscovered elements and predicted their properties
rearranged the table so elements with similar properties fell into groups
how is the modern periodic table arranged?
by electronic structure
how does the modern periodic table differ from mendeleevs?
details such as how many electrons protons and neutrons
mendeleev had no knowledge of subatomic particles
give an everyday example of an exothermic reaction
hand warmers, self heating can
give an everyday example of an endothermic reaction
cold pack
what is activation energy?
the amount of energy needed to get a reaction started
this energy is needed to break bonds so new ones can form
what would an exothermic reaction diagram look like?
the energy needed to break bonds is less than the energy released forming new bonds
\_\_\_\_ e l / \ n l \_\_\_\_/ \ e l \ r l \\_\_\_\_\_\_ g l y l\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ time
describe the energy changes in a reaction
energy is needed to break bonds
energy is released when bonds are made
what does an endothermic reaction diagram look like?
the energy needed to break bonds is more than the energy released from forming bonds
e l ____
n l / \
e l / \_____
r l /
g l ____/
y l__________________
whats the equation for calculating the energy transfer/change?
energy transfer= energy taken to break bonds-energy released making bonds
how can we increase the rate of reaction
by increasing the amount of reactant we are putting in. This means their are more particles so their will be more collisions so will increase the rate of reaction
how do catalysts work?
they provide an easier path for the chemical reaction that provides less activation energy
describe an isotope
has the same atomic structure but different number of neutrons
how do you calculate the relative atomic mass of two isotopes?
relative atomic mass= (atomic mass of isotope 1 x abundance of isotope 1)+(atomic mass of isotope 2 x abundance of isotope 2)
_________________________________________________________________________________________________________________
100
