C1 - Atomic Structure Flashcards
What is an Atom?
An atom is a tiny particle of which all substances are made from.
What is an Element?
An element is a substance made up of only one type of atom.
118 elements
92 naturally occurring
26 man-made
What is the name of the table where all the elements are arranged?
The Periodic Table
What is a compound?
A substance made up of 2 or more types of atoms, that have chemically bonded.
Who first described atoms as solid spheres?
John Dalton
What are the 3 main developments of the structure of an atom?
- JJ Thompson’s Plum Pudding Model
- Rutherford’s Nuclear model of the atom
- Bohr’s model of the atom
What is the Plum Pudding Model?
A sphere of positive charge with electrons embedded in it.
What is Rutherford’s nuclear model of the atom?
A dense positively charged nucleus with electrons orbiting around it.
Rutherford also added empty space.
After Bohr’s model of the atom, who discovered that there are neutrons in the nucleus?
James Chadwick
What are the 3 components of an atom?
Protons (+) (nucleus)
Electrons (-) (outside nucleus)
Neutrons (0) (nucleus)
What is the relative mass of a protons, neutron and electron?
Protons = 1 Neutrons = 1 Electrons = Almost 0
Why are atoms always neutral?
Because the number of protons is always equal to the number of electrons.
What is an Ion?
An Ion is a charged atom or group of atoms.
What is an Isotope?
Isotopes are atoms of the same element with different numbers of neutrons.
E.g there are 3 Hydrogen Isotopes
Hydrogen - 1 neutron - 1 proton - 1 electron
Deuterium - 2 neutrons - 1 proton - 1 electron
Tritium - 3 neutrons - 1 proton - 1 electron
Which physical property differs in pure samples of different isotopes of the same element?
Density - the density of the nucleus varies due to the different number of neutrons.
Chemical properties, caused by the electronic structures of atoms, remain the SAME.
Why are Elements in Group 1 and 7 the most reactive?
Because they need to either gain or lose 1 electron to become electronically stable as an Ion.
What is Bohr’s model of the atom?
A dense nucleus with electrons arranged in fixed energy levels. This is the current model.
What do electrons orbit the nucleus in?
Electronic shells
How many electrons can the first shell contain?
2 electrons
How many electrons can the second and third shell contain?
8 electrons
How many electrons can the fourth and above shell contain?
8 electrons
What is the electronic arrangement of Oxygen?
2.6
8 electrons in oxygen as the atomic (proton) number is 8.
Maximum of 2 electron in the first shell so the second shell has 6 electrons. 2 + 6 = 8
What does the reactivity of an element depend on?
The number of electrons in the outermost shell - the group number.
Group 1 have 1 electron in the outer shell and Group 2 have 2 electrons in the outer shell. The trend continues.
