Covalent Bonding Flashcards
What did Johann Dobereiner develop?
Groups of 3 elements with similar properties
Covalent bonding is ……….. ONLY
Non metals
What did John Newlands do?
Arranged elements in order of their atomic masses - noticed similarities between elements
What did Mendeleev do?
Arranged elements periodically so elements with similar properties were grouped together
How did Mendeleev achieve what he did?
He had to leave some gaps for elements which had not been discovered - he was able to predict what these elements would be like
What is a group?
A vertical column
What do elements in the same group have?
Same number of electrons in their outer shell
What is the number of electrons in the outer shell the same as?
The group number
What is a period?
Horizontal row
What does the period tell us?
How many electron shells there are in an atom of an element
Molecules with single covalent bonds
Hydrogen, water, methane
Why do carbon dioxide and water have low melting points?
The intermolecular forces are weak so only a small amount of energy is needed to separate them
Why don’t carbon dioxide and water conduct electricity?
There are no free electrons
Covalent bonding is when….
Nonmetals combine, they share a pair of electrons so they have filled their outer shells
Ionic bonding is when….
A metal loses electrons making positive ions
A nonmetal gains electrons making negative ions
The ions attract each other
