atoms and elements Flashcards
what is an atom?
smallest unit of an element
what happens with the charge of electrons and protons in a neutral atom?
they have the same charge
how are elements organised?
by their atomic number - no. at top of square
what are the components of an atom?
(1) atomic number = number of protons
(2) mass number = no. of protons + neutrons in nucleus
(3) number of neutrons = mass number minus atomic number
what are the rows of the periodic table?
horizontal rows are called PERIODS
what are the columns of the periodic table?
vertical columns are called GROUPS
whats so special about periods huh
elements in same period have same number of electron shells
why are groups cool and cutesy
elements in same group share the same chemical and physical properties
what are valence electrons?
- number of valence electrons determines what group an atom is in
- electrons in OUTER shell of an atom
- these are the electrons that transfer/are shared when atoms bond
GROUP ONE
ALKALI METALS
- shiny, easily cut (Na)
- react violently with water
- NEVER found as free elements in nature, always bonded with other elements
GROUP TWO
ALKALI EARTH METALS
- never found uncombined in nature
- shiny, harder consistency than alkali metals
GROUPS THREE - TWELVE
TRANSITION METALS
- good conductors of heat + electricity
- form ions of different charges [Cu (l) and Cu (ll)]
- compounds of transition metals usually brightly coloured
GROUP FOURTEEN
CARBON FAMILY
- has wide range of properties; non-metal carbon, metalloid silicon, metal lead
- most EMERGENCY element in this group is carbon, which exists as allotropes
- carbon in building block of organic molecules
GROUP SEVENTEEN
HALOGEN FAMILY
- has seven valence electrons, making them most reactive non-metals
- never found free in nature
- react most with alkali metals (to form salts)
GROUP EIGHTEEN
NOBLE GASES RAAAAH
- non-reactive
- called ‘inert’ (doesn’t react)
- found as atoms in earths atmosphere
