C4.1 Flashcards
atoms of each element have what?
different proton numbers
what does arranging the elements in order of their proton number give?
repeating patterns in the properties of elements
what happened to early attempts to find connections between the chemical properties of the elements?
they were dismissed by the scientific community
dobereiner 1829
triplets or trains of elements seemed to exist with similar properties
new lands 1866
octave pattern-every 8th element to be similar
mendeleev 1871
his version of periodic table
made predictions about properties and mass of yet discovered elements
left gaps to be filled when they were found
mendeleev 2 rules
- order of relative atomic mass
* chemically similar in same group
2 elements mendeleev predicted would exist and years
Gallium 1875
Germanium 1886
what is a period
a row of elements
alkali metals properties
shiny when freshly cut but tarnish rapidly in moist air due to reaction with oxygen
where must alkali metals be stored to stop reaction with oxygen
in oil
melting and boiling point as go down group
get lower
alkali- hardness as go down group?
get softer
Lithium reactivity
gentle fizzing
Na reaction
faster fizzing
potassium reaction
vigorous fizzing
Lithium flame
bright red
Na flame
bright yellow
potassium flame
lilac
alkali- reactivity as go down group?
more reactive
alkali metals react with water to form what?
hydrogen and an alkaline solution of a hydroxide
Forumula- MOH
alkali metals react vigorously with chlorine to form what?
colourless crystalline salts
formula- MCl
Na and Cl come together to form colourless crystalline salt formula
Sodium Chloride
why should you never handle alkali metals with hands
how to control?
corrode or explode in hand when reacts with water (sweat) - scars
•use forceps
why do alkali metals get more reactive as go down group?
outer electron is further away from the influence of the nucleus and so an electron is lost more easily
