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