C1(1.1-1.8) Atomic Structure Flashcards
What is an atom?
-An atom is the smallest part of an element that can exist
What is Dalton’s model of the atom
-Atoms as solid spheres that could not be divided into
smaller parts
What is the plum pudding model of the atom?
-Sphere of positive charge with negative electrons
embedded in it
What did scientists discover in the alpha scattering
experiment?
-Some alpha particles were deflected by the gold foil –
this showed that an atom’s mass and positive charge
must be concentrated in one small space (the nucleus)
Describe the nuclear model of the atom.
-Dense nucleus with electrons orbiting it
What did Niels Bohr discover?
-Electrons orbit in fixed energy levels (shells)
What did James Chadwick discover?
-Uncharged particle called the neutron
Where are protons and neutrons?
-In the nucleus
What is the relative mass of each sub-atomic
particle?
-Proton: 1, neutron: 1, electron: 0 (very small)
What is the relative charge of each sub-atomic
particle?
-Proton: +1, neutron: 0, electron: −1
How can you find out the number of protons in an
atom?
-The atomic number on the Periodic Table
How can you calculate the number of neutrons in
an atom?
-Mass number – atomic number
Why do atoms have no overall charge?
-Equal numbers of positive protons and negative
electrons
How many electrons would you place in the first,
second, and third shells?
-Up to 2 in the first shell and up to 8 in the second and
third shells
What is an element?
-Substance made of one type of atom
What is a compound?
-Substance made of more than one type of atom
chemically joined together
What is a mixture?
-Two or more substances not chemically combined
What are isotopes?
-Atoms of the same element (same number of protons)
with different numbers of neutrons
What are the four physical processes that can be
used to separate mixtures?
-Filtration, crystallisation, distillation, chromatography
What is relative mass?
-The average mass of all the atoms of an element
