C2.1 - C2.6 Periodic Tabel✔️ Flashcards
Issues with Argon is mendleeves tabel?
Argon did not fit patern - has greater atomic weight then potassium - ordering by weight would mean a nobel gas would be in the group with reactive metals - to fix it he simply changed their order to keep elements with similar properties in the same group.
Discovery of Isotopes explained oddly heavy atomic weight
What is the order of the Perodic table today?
-order of atomic number
-arranged in vertical groups - 8 main groups - tell number of electrons on outershell
Physical proprties of Alkali metals?
-very low density - float on water
-very soft - silvery/shiny surface
-melt and boil at low temp
Chemcial properties of the halogens?
-exist as diatomic (pairs)
-react with non metals - to gain an electron
-less reactive down group
-“More reactive halogen displaces less reactive halogen from solution of salts”
Group 7 reactivity?
-reactivity decreases down group
-less atractive force - harder to gain extra electron - outershell shielded by inner shells - reduces electrostatice attraction - greater distance from nucleus
5 physical properties of Transision metals?
-good electric and thermal conductors
-hard and strong
-high densities
-high melting points (except mercury)
-less reactive then group 1
What is an alloy?
Mixture of metals - contain at least 1 transition element
Compounds of transition elements?
-form coloured compounds
-element usually contain roman numbers - because they can form more then 1 ion
-important in chemical industry as catalysts
Why do the halogens melting and boiling points increase going down the group?
exist as simple molecules held together by weak intermolecular forces of attraction - increase going down the group because molecules become larger - stronger surface area of contact between molecules resulting in stronger intermolecular forces
Order of John Daltons perodic table?
Arranged in order of their atomic weight
Order of John newlands perodic table in 1864?
Arranged also in order of mass but noticed proprties of every 8th element seemed similar - produced Law of Octaves
What was wrong with John Newlands Law of Ocataves?
-assumend all the elements had been found
-pattern only worked up to calcium before it broke down
Order of Mendeleevs table?
Arranged in order of atomic wights and arranged them so that a perodic pattern in their properties could be seen - Argon did not fit so he kept elemts with similar properties in the same group
Why was Mendeleevs table accepted?
-he left gaps for elements not yet discovered
-used his table to predict their properties
-when elements were discovered they closley matched his predictions
Chemical properties of Alkali metals?
-always form ionic compounds (1+) - react with non metals to loose electron - genreally white and dissolve in water
-very reactive with water
