atomic mass
the average mass of one atom of the element
in what order did Mendeleev arrange the elements in the Periodic table
He arranged them in order of increasing atomic mass
periodic table
regular repeated pattern
nucleus
the core of an atom
neutron
a particle with a no charge inside the nucleus
protons
a small particle with a positive charge inside the nucleus
electron
a pparticle with a negative charge outside the nucleus
atomic number
the number of protons in its nucleus
atomic mass unit
the measure of the particles in atoms
what does each square in the periodic table contain?
chemical symbol, name, atomic number and atomic mass
what can you predict about an element from its position in the periodic table?
an elements properties can be predicted from its position on the periodic table
chemical symbol
an element name that usually contains one or two letters
group/ families
elements in a column
periods
each horizontal row across the table
valence electrons
the number of electrons on the last energy shell
what happens to the number of valence electrons as you move from the left to the right on the periodic table?
they become less reactive
how to chemists classify metals?
based on physical properties
malleable
material that can be pounded into shapes
ductile
material that can be pulled out or drawn into a wire
conductors
metals that can transmit heat and electricity easily
magnetic
several metals that are attracted to magnets and can be made into magnets
reactivity
the ease and speed with which an element combines or reacts with other elements and compounds
alloy
a mixture of metals
metals in a group or family have _____ properties
similar
alkali metals
reactive metals in group one that are never found uncombined in nature
alkaline earth metals
group two metals that are not as reactive as group one metals but still very reactive
transition metals
groups three through twelve that form a bridge between very reactive metals and less reactive metals
metals in mixed groups
groups thirteen through sixteen (includes metals, nonmetals and metalloids)
lanthanides/ actinides
located below the periodic table known as the rare earth elements (periods 6 &7)
nonmetals
the elements that lack most of the properties of metals
where are non metals located?
located to the right of the zig zag line of the periodic table
What is a difference between metals and nonmetals?
physical properties
diatomic molecules
two identical atoms
non metals can form compounds with ____________________.
nonmetals
Group 14
the carbon family each element has 4 electrons
Group 15
the Nitrogen family each element has 5 valence electrons
Group 18
contains nonmetals exclusively
Group 16
Oxygen family contains 6 valance electrons
Group 17
Halogen Family/ 7 valence electrons
Group 18
Noble Gasses / don't gain , loose or share their electrons
metalloid
has some of the characteristics of metals and non metals
what is metalloids most useful property
ability to conduct electricity
semiconductor
substances that under some conditions can carry electricity
plasma
state of matter when atoms are stripped of their electrons and the nuclei are packed closely together
nuclear fusion
atomic nuclei combine to form a larger nucleus releasing huge amounts of energy in the process
supernova
tremendous explosion that breaks apart a massive star