Periodic Table Flashcards
What did Robert Boyle define an element as in 1660
A substance that cannot be broken into any simpler substances
What is one very important feature of the modern periodic table that makes the study of chemistry easier
Elements with similar properties are grouped together
Elements are arranged in
Increasing order of atomic number
Real name for mass number
Relative atomic mass
Number of protons
Atomic number
Vertical columns
Groups
Horizontal rows
Periods
How many man groups
8
D-block made up of
Elements in groups II and III
Short vertical columns in d-block
Sub-groups
Group I
Alkali metals
Group II
Alkaline Earth metals
Group VII
Halogens
Group 0
Noble gases
Elements in 2 groups
Metal and non metals
In general metals on…
Left of stairs
In general non metals on…
Right of stairs
Top step of stairs
B (5)
Bottom step of stairs
At (85)
Elemis bordering stairs…
Have similar properties to metals and non metals
2 examples of elements bordering stairs
Si(14) and age (32)
Most reactive metals
Group I alkalis
Most reactive non-metals
Group VII halogens
What did Dobreiner come up with
Dobreiners Law of Triads
What did Dobreiner note in his law of triads
Certain groups of 3 elements were related to their relative atomic mass
2 examples of triads
Lithium sodium potassium
Sulfur selenium tellurium
Devi union of a triad
A group of 3 elements with similar chemical properties where the relative atomic mass of the middle element is approximately the average of the other two
Ar
Relative atomic mass
What did Newland come up with
Newlands law of octaves
Newlands law of octaves
Each 8th element, starting from any given knee was similar in properties ti the first one
Where did newlands law of octaves work
For the first 16 elements
Why does newland slaw of octaves not work for the modern periodic table
Noble gases of group 0 are known now,
It is now every 9th elements that is similar
How did newlands make an important contribution
He showed that the elements could be arranged in a table
What did Mendeleev come up with and how
Mendeleev’s periodic table
He listed the known elements in order and put those with similar properties in vertical columns called groups
What gave rise to his periodic law
He noted that similar properties recurred periodically for every eighth element
What did Mendeleev do against his idea of increasing Ar and why
He put tellurium (Te) before Iodine (I) so that they would have similar properties to their groups
How was Mendeleev smart
He predicted the existence of many elements and left gaps for them and most were accurate eg. Germanium and Gallium
Mendeleev’s periodic law
When elements are arranged in order of Ar, their properties repeat at regular intervals or periodically
3 differences between Mendeleev’s and modern
Atomic number vs, Ar
No gaps in modern vs only 63 known back then
Number of blocks eg.d-block vs a rectangle
What provided mosely with an indirect method I’d measuring the number of protons in an atom
He noted that the frequencies of x-rays emitted by atoms of different elements varied with the quantity of positive charge (number of protons)
What did Mosley do with the periodic table
Put it in order of increasing atomic number and he showed that elements fell easily into their correct groups
At room temperature elements…
2 are liquid; mercury (Hg) and bromine (Br)
11 gases
Rest are solid
Nature of light
Consists of particles called photons which have energy but no mass and which travel in waves
Different colors are because of…
Different wavelengths, frequencies and energy contents
Read light
Long wavelength
Low frequency
Low energy
Violet light
Short wavelength
High frequency
High energy
How is a continuous spectrum formed
If white light is lasses through a prism as is dispersed a band of colores blend into each other
How is the emission spectrum of hydrogen formed
A sample of H2 gas that is través in a discharge tube is energized using electricity, it glows to give a faint light which is dispersed in a prism of a spectroscope
What does a line spectrum look like?
A few narrow band of light against a dark background
Emmisiom spectrum
The dispersed light from any source
Simplest emission line spectrum
From hydrogen gas
How are line spectrums unique?
Each element has its own emission spectrum which is different to that of any other element
Street lights
Sodium in a discharge tube
3 series in the emission spectrum of hydrogen
Lyman Balmer and paschen
Which series is ultra violet in
Lyman series
Which series is violet blue green and red in
The Balmer series (visible)
Which series is infra red in?
Paschen series
Electron in its lowest energy leve,
Ground state
Electron occupies…
Fixed energy levels
Moves from ground state up to…
Excited state
E=
E1-E2=hf
The fact that the line spectrum kr hydrogen consists of only a few lines of light of different energies shows…
The electrons of the hydrogen atom can only lose certain distinct amounts of energy and cannot lose a whole range I’d energies
The energy of the electron is said to be….
Quntisised
Why do we see all the lines at the same time in a hydrogen emisión spectrum
There are millions of hydrogen atoms in the discharge tube all doing millions of movements at the same time
Lyman series
A series of ultra violet lines caused by electrons falling back to n=1 level
Balmer series
A series of visible (violet, blue, green and red) lines caused by electrons falling back to n=2
Paschen
A series of infa red lines caused by electrons falling back to n=3
In Bohr’s theory of the atom what explained why electrons. Do not crash into the nucleus
The electron does not give out or take in energy unless it’s moving to another allowed energy level
The electron will move to a higher energy level if
It receives the exact energy equal to the difference between both energy levels
The electron will move to a lower energy level if
It loses an amount of energy exactly equal to tge difference between both energy levels
plancks constant
h
6.63 x10 -24 Js
f
Frequency of light emitted
Definition of energy level
A fixed or def8nite amount of energy that an electron is allergic to have in an atom
What causes elements to have unique emission line spectra
Each element has different numbers and different types I’d transitions
Electronic transitions
Movement from one energy level to another
How can you see an absorbtion spectrum
When whit slight is passed through a sample of it and the light is observed using a spectroscope
Why does it change when it goes through
It absorbs light of certain wavelengths which means that they don’t pass through
The absorbtion spectrum of an element is the…
Exact opposite of the emission spectrum
It’s photographic negative
Absorbtion spectra are used in a laboratory technique called
Atomic absorption spectrometry
How do you measure the concentration of sodium using atomic absorbtion spectrometry
One would Energie’s a sample of pure sodium and allows the light to pass through the sample contaminated with sodium.
Only other sodium atoms will dully absorb the light while the others will reject it.
2 known uses for atomic absorbtion spectrometry
The analysis of water for lead and mercury
In forensic science eg. Analyzing gun powder residue on clothes
Sublevels in n=1
1s
Sublevels in n=2
2s, 2p
Sublevels in n=3
3s, 3p, 3d
Sublevels in n=4
4s, 4p, 4d, 4f
Electrons in s
2
Electrons in p
6
Electrons in d
10
Electrons in f
14
Aufbau principle
Electrons must occupy the lowest energy levels available
Sub-energy level
A subdivision of a main energy level and consists of one or more orbitals of the same energy
What did Louis de Broglie state?
That all moving objects has a wave motion associated with that movement
Heisenberg’s uncertainty principle
It is not possible to determine at the same time the exact position and velocity of an electron
What did Schrodinger do? (Atomic orbitals)
Used mathematical equations to predict where an electron might be found in spaces outside a nucleus
He plotted these points on 3-D polar diagrams
Orbital
A region in space around a nucleus where there is high probability of finding an electron
The Pauli Exclusion Principle
Not more than 2 electrons can occupy an orbital and thrh cam only do this if they have opposite spin
Shape of s orbital
Sphere
Shape of px orbital
Dumbbell (horizontal)
Shape of py orbital
Dumbbell vertical
Shape of Pz orbital
Dumbbell
On z axis (diagonal)
Hunds rule
When two or more orbitals of equal energy are available to electrons, the electrons will occupy these singly before occupying them in pairs
D-block metals
Elements which have their highest energy electrons in a d-sublevel
Transition metals
Meats which form at least one ion which has electronic configuration ending in an incomplete sublevel
Transition metal.., (3)
Have variable valiency (exist as different ions)
Exist as colored compounds
Act as catalysts
2 exception of aufbau principle
Copper Chromium Cu; Ends in 4s1, 3d10 Cr; ends in 4s1, 3d5 More stable ending in full or have sublevels
Why is there no yellow line in the line spectrum of hydrogen
Their is no corresponding energy loss by a hydrogen atom electron that releases light with a frequency or wavelength that would appear as yellow light
Flame test result
. Barium
Yellow/green
Flame test result
. Calcium
Orange/red
Flame test result
. Copper
Green/blue
Flame test result
. Sodium
Yellow
Flame test result
. Potassium
Lilac
Flame test result
. Lithium
Crimson
Why are disposable wooden splints used in falm test
To prevent cross contamination
4 limitations of Bohr’s theory
Only worked well for hydrogen
Could not explain splitting I’d certain emission line (sublevels)
Did not take into account the wave motion of the moving electron
At odds with Heisenberg’s uncertainty principle
Atomic radius
Half the distance between the nuclei of two atoms of the same element that are joined together by a single covalent bond
Atomic radius across a period
Decreases
Atomic radius down a group
Increases
Why does atomic radius decrease across a period
Increasing nuclear charge pulls outer electrons in closer to nucleus
Reasons for atomic radius increasing going down a group
Screening effect (more electrons) Just bigger (more electrons) (There is more nuclear charge but cancelled out by^^)
Why are group 1 more reactive going down the group (lose electrons when reacting) (2)
Atomic radius increases (further away from pull of nucleus)
Increased screening
Why are group 7 elements live reactive doing down the group (gain electrons when reacting )
Atomic radius increases, new electrons can’t get close to nucleus to be held tightly
Extra screening makes it more difficult to gain electrons
Nuclear charge
Number if protons (+) pulling in electrons (-) towards the nucleus
First ionisation energy
The energy needed to remove the most loosely bound electron from each atom in one mole or gaseous atoms in their ground state
First ionisation energy represent as (2)
X°(g)
Or
X+(g) + e-1
Second ionisation energy represented as (2)
X+ (g)
Or
X+2 (g) + e-1
Third ionisation energy represented as
X+2(g)
Or
X+3 (g) + e-1
Second ionisation energy
The amount of energy required to remove the most loosely bound electrons from each singly charged ion in one mole of gaseous ions
Ion ionisation energy going across a period…
Increases
Ionisation energy going doing a group
Decreases
Why does ionisation energy increase going a across a period (2)
Increased nuclear charge (stronger pull)
Smaller atomic radius (closer to nucleus)
2 exceptions to general rule of ionisation energy increasing across a period
Be and N, very stable, full outer sublevels , high energy needs
Temporary decrease after these elements
Down a group decreasing ionisation energies
Larger atomic radius
Extra screening
Successive ionisation energies of an element
The 1st, 2nd, 3rd, 4th etc. Ionisation energy of the same element (electrons being removed one by one)
When are successive ionisation energies increasing (3)
Always increasing
Very large increase from one main energy level to another eg. n=2 and n =3
Higher when taking from a full sublevel eg. 2p6
Except for spectroscopic experiments carried out by Bohr, what gives strong evidence that electrons have distinct energy levels?
The huge increases in some successive ionisation energies
