Atoms Elements and Compounds - Term 1 Flashcards
Relative atomic mass
The weighted mean mass of an atom of an element compared with one twelfth of the mass of an atom of carbon 12
Properties of a compound
Difficult to break apart (chemically bonded)
Made of two or more different elements
All compounds are molecules but not all molecules are compounds
Number of circles (shells)
Period number
Number of electrons on outer shell
Group number
Properties of an element
A pure substance made of one type of atom
Cannot be broken down into anything smaller
Elements of same type can go together to make molecules
Total number of electrons
Atomic number
Mixture
Two or more elements / compounds present but not chemically combined
Properties of metal
Shiny ductile (bent into a wire) malleable (hammered into a shape) high melting and boiling points good Electric and thermal conductors
Proton neutron and electron relative mass
1,1,1/1840
Proton neutron and electron relative charge
1,0,-1
Numbers of protons =
Number of electrons / atomic number
What determines the type of atom
Number of protons / atomic number
Isotopes
Atoms of the same element that have different number of neutrons
Energy levels also known as
Shells
Mass number =
Number of protons + neutrons
If an atom loses electrons it becomes _____________ charged . This particle is called a ___________ ______
Positively
Positive ion (cation) (+1)
If an atom gains one electron it becomes ___________ charged. This particle is called a ________ _____.
Negatively
Negative ion (-1)
Democritus
Imagined a substance that could not be cut into smaller pieces indefinitely, leaving you with an indivisible “atomos”
John Dalton
Matter always combined in fixed ratios = Atoms of one element are the same, and compounds are different elements in a fixed ratio
JJ Thompson
Discovered electrons, made plum pudding diagram.
Plum pudding diagram
Atoms were made of positive matter and had negative electrons scattered across , like plums in a plum pudding.
Ernest Rutherford
discovered nucleus
Nucleus model
The nucleus model has a tiny positive nucleus (no neutrons)
Niels Bohr
discovered shells