C1.2 - Atomic Structure Flashcards
What is an atom?
The smallest particle of an element that still has its chemical properties
What is a molecule?
Two or more atoms joined together by attractive forces called chemical bonds
How is the size of an atom given?
Its atomic radius
What is an atom’s bond length?
The distance between the centres of two joined atoms
What does most of the atom consist of?
Empty space
What are the three subatomic particles in an atom?
Proton
Neutron
Electron
What is the relative mass of a proton?
1
What is the relative mass of a neutron?
1
What is the relative mass of an electron?
0.0005
What is the relative charge of a proton?
+1
What is the relative charge of a neutron?
0
What is the relative charge of an electron?
-1
Why is most of the mass of an atom in the nucleus?
Most of the atom is empty space
Describe the structure of an atom
Contains 3 subatomic particles - proton, neutron, electron
Protons are positively charged and found in the nucleus
Neutrons are neutrally charged and found in the nucleus
Electrons are negatively charged and found orbiting the nucleus in shells
What is the bottom number of a chemical symbol?
Atomic number (Z)
What does the atomic number tell us?
How many protons are in the nucleus of an atom
What is the top number of a chemical symbol?
Mass number (A)
What does the mass number tell us?
How many neutrons and protons there are in the nucleus of an atom
How do you work out the number of protons in an element?
Atomic number
How do you work out the number of neutrons in an element?
Mass number - atomic number
How do you work out the number of electrons in an atom?
Atomic number
What are isotopes?
A form of an element with the same number of protons and electrons but a different number of neutrons
Different mass number
What do isotopes of the same element have in common?
Have the same chemical properties
What are ions?
Charged particles
Formed when an atom loses or gains electrons
What did John Dalton do for the atomic model?
. Said all atoms of an element are identical
. Different elements have different types of atom
. Imagined them as tiny solid balls
What did J.J Thompson do for the atomic model?
Came up with the plum pudding model said atoms contain electrons
Atoms have a neutral overall charge
Which subatomic particle did J.J Thomson discover and how?
Electron (in 1987)
He found that beams of cathode rays changed directions in electric and magnetic fields
Concluded that cathode rays were actually tiny particles that were negatively charged and smaller than atoms
What was J.J Thomson’s plum pudding model?
Atoms are spheres of positive charge
Electrons dotted inside it, like pieces of fruit in a cake
What did Ernest Rutherford do for the atomic model?
An atom has a positively charged nucleus containing most of its mass
Electrons orbit the nucleus
What was the alpha particles experiment?
In 1909
Fired light beams of alpha particles at thin gold foil
Most went straight through
Some changed direction slightly
Some came straight back
What did the alpha particles experiment suggest?
An atom has a positively charged nucleus containing most mass
Electrons orbit this nucleus
What did Niels Bohr do for the atomic model?
Showed that electrons occupy fixed energy levels, or shells, around the nucleus
Are periods on the periodic table horizontal or vertical?
Horizontal
Are groups on the periodic table horizontal or vertical?
Vertical
