Atomic structure- main focuses- part 1 Flashcards
In the past, what were elements arranged by?
1) physical and chemical properties
2) relative atomic mass
When were protons and electrons discovered?
in the 20th century
Who left gaps in the periodic table?
Dmitri Mendelleev
Why did he leave gaps in the periodic table?
To predict new elements
What is the modern periodic table laid out in?
increasing atomic number
What are groups?
The vertical columns, they tell you how many electrons are in the elements outer shell
What are periods?
The rows, each period represents another full shell of electrons
What do metals form when they react?
Positive ions
What determines how a metal reacts?
Their electronic structure
What are metals properties?
1) They are strong
2) Great at conducting heat and electricity
3) high boiling and melting point
What are non-metals properties?
1) Brittle
2) generally don’t conduct electricity
3) lower density
What are transition metals?
found between group 2 and 3, they have properties of a typical metal
What are transition metals special properties?
1) can have more then one ion
2) often coloured
2) often make god catalysts
