atoms, elements and compounds 1 Flashcards
Define element
a substance made of only one type of atom
how many elements are there?
118
define compound
2 or more elements chemically combined in a fixed ratio
define mixture
2 or more elements and/or compound not chemically combined
define relative atomic mass
mass of isotopes according to natural abundance
Examples of relative atomic mass
Copper 63.5
example of isotopes
Chlorine 35 and 37
how do you work out relative mass?
(word equation)
(say ‘a’ is atomic mass and ‘n’ is natural abundance)
( a1 × n1)/100 + (a2 × n2)/100
relative mass and charge of electron
1/1837 -> relative mass
-1 -> relative charge
relative mass and charge of neutron
0 -> relative charge
1 -> relative mass
relative mass and charge of proton
1 -> relative mass
+1 -> charge
how many electrons on inner, 2nd and 3rd shell?
1 -> 2 electrons
2 and 3 -> 8 electrons
mass number (what)
nucleus - protons + neutrons
atomic number (what)
protons and electrons
democritus discovery:
atomos (greek indivisible) smallest thing everything is made up from
jd (who) discovery
John Dalton
atoms = tiny, invisible, solid balls
compounds = different types
elements = same type
who and how discovered electrons and how did they thing they were arranged ?
JJ Thompson, cathode Ray, plum pudding model
how and who disproved the plum pudding model?
Ernest Rutherford, gold foil experiment using alpha rays, the nucleus is positive
who discovered neutrons and their charge?
James Cadwick
how many electron in neutral atom?
same as protons
define isotope
type of aton with unstable number of neutrons, varient of element
why do atoms contain an equal number of protons and electrons, and what are they called if they don’t
?
So atoms have a neutral charge (balance out), if they are not neutral they are called ions
how is the periodic table arranged?
Arrangement of the elements in order of atomic number
define group and give examples
The columns of the periodic table are called groups. Members of the same group in the table have the same number of electrons in the outermost shells of their atoms : alkali metals, alkali earth metals, halogens, noble gases
define period
a row of chemical elements. All elements in a row have the same number of electron shells. Each next element in a period has one more proton and is less metallic than its predecessor
