Chapter 2 Flashcards
(23 cards)
What does the periodic table show
Names and symbols of elements
Where are metals and non metals on the periodic table
Metals on the left, non metals on the right
Another name for group 1 elements and info abt them
Alkali metals. Very reactive, reactive vigorously with water. Top to bottom, reactivity increase, melting point decreases. Always produce metal hydroxide (alkaline) and hydrogen when reacting with water
What’s an element
Cannot be broken into other substances. One type of atom
What is a compound
Substance made of two or more elements, chemically bonded together
What is a mixture
Two or more substances not chemically bonded. They are easily separated
What is a physical property
Describes how substance behaves generally.
What is a chemical property
How a substance behaves in chemical reactions
Properties of metals
Good conductor of electricity and thermal energy
Shiny
Malleable
Ductile
Sonorous when solid
Most have high melting and boiling points
Some react with oxygen to form metal oxides
Properties of non metals
Opposite of metals usually
Low boiling points therefore usually a gas at room temp
Poor electrical and thermal energy conductors
Dull
Brittle
Not sonorous
How many elements had been discovered by 1860
Around 60
What did John dalton do?
Suggested that atoms of each element had different mass
What did Stanislaw Cannizzaro do?
Worked out the atomic masses of elements
What did Mendeleev do?
In 1869, Mendeleev eventually correctly ordered the elements creating the first periodic table he left gaps for undiscovered elements
When was the table almost complete
1925
Sub atomic particles and their charge
Proton + 1
Neutron 0
Electron -1
How to calculate relative mass of atom
Add together amount of protons and neutrons
How are things ordered in periodic table
Henry Moseley showed elements positions depended on number of protons not atomic mass
Electronic structure
Protons and neutrons in nucleus electrons orbit around 2 in first shell then 8 in the other shells
What is group number decided on
Amount of electrons in outer shell
Covalent bonding
Exist in molecules contribute 1 electron to shared pair each share of 8 electrons in outer shell the shell is full making the molecule stable most non metals exist as molecules as do compounds
Ionic bonding
Metal joined to non-metal one electron moves to outer shell of other makes two particles with electrical charge, called ions outer shells are full so it is stable electrostatic attraction between positive and negative ions holds the particles together
