The Periodic Table Flashcards
How were elements arranged in the 1800’s?
They were arranged by atomic mass and the physical + chemical properties
What did Dmitri Mendeleev do?
He ordered elements he knew at the time in order of atomic mass but re-arranged them with similar chemical behaviour
He left gaps for undiscovered elements which he knew existed and predicted their chemical behaviour
What did Henry Moseley?
Identified the atomic number which lead to the modern periodic table - in order of increasing atomic number
What determines the position on the periodic table?
Proton number determines the position on the periodic table
What does the number of electrons in the outer shell predict?
It determines the chemical behaviour of an element
What does the group number determine?
The number of electrons in the outer shell of the atom
How do noble gases act in terms of reactivity?
They are unreactive as they have a stable electron arrangement - full outershell
What are vertical columns called in the periodic table?
Groups
What are horizontal rows called in the periodic table?
Periods
What are properties of group 1 - alkali metals?
Low density, boiling and melting point
Metal ion carries a charge of +1
Compounds tend to white crystalline solids which dissolve in water
Shiny, soft, silver metals that dissolve in water
Reactivity increases down the group
Why does the reactivity increase down group 1 - alkali metals?
They have 1 outer shell electron
For example lithium when it reacts with another elemt it’s less reactive as it’s harder to break the bond as there’s less distance and shielding between the electron and the nucleus
What are properties of group 7 - the halogens?
Form ionic salts with metals - halide ions carry a charge of -1
Form covalent molecular compounds with non-metals
They exist diatomically
Reactivity decreases down the group
Why does the reactivity decrease down group 7 - the halogens?
Atoms get larger going down the group
Outer shell gets further away from nucleus and is shielded by more electron shells
The further away the positive attraction of the nucleus is the harder it is to attract another to complete a full outer shell
What are physical properties of transition metals - between groups 2 and 3?
Good conductors of heat + electricity
Hard + strong
High density
High melting point in comparison to group 1
What are chemical properties of transition metals - between groups 2 and 3?
Less reactive than group 1 metals
Tend to form coloured compounds
Transition metals + compounds tend to be used as catalysts
Can form ions with different charges
