Chemistry GCSE: C1 Atomic Structure and the Periodic Table Flashcards
What is a mixture?
Give examples of mixtures.
Two or more elements or compounds that are not chemically bonded.
Examples of mixtures:
Tap water (water and a variety of ions)
Sea water (water and a variety of ions including sodium and chloride ions)
Milk (water and a variety of fats, proteins and sugars)
Steel (iron, carbon and other metals)
What is a compound?
Give examples of compounds.
Two or more elements that are chemically bonded.
Examples of compounds:
Covalent compounds: Carbon dioxide, water, carbon monoxide, methane, sulfur dioxide, nitrogen dioxide etc.
Ionic compunds: Sodium chloride, sodium hydroxide, iron oxide, calcium carbonate etc.
What is the easiest way to identify whether something is an element?
Look in the periodic table.
What is a molecule?
Two or more atoms chemically bonded together.
These can be atoms of the same element (e.g O2) or atoms of different elements (CO2).
What three types of subatomic particle are atoms made from?
Protons
Neutrons
Electrons
What is the charge of a proton?
Positive
+1
What is the charge of an electron?
Negative
-1
What is the charge of a neutron?
Neutral
No Charge
0
What is the overall charge of an atom? Explain why atoms have this charge.
Neutral (no charge, 0)
Because all atoms have equal numbers of positively charged protons and negatively charged electrons, so they cancel each other out.
What is the mass of a proton?
1
What is the mass of an electron?
0 (no mass)
What is the mass of a neutron?
1 (the same as a proton)
Where are protons found in an atom?
In the nucleus
Where are neutrons found in an atom?
In the nucleus
Where are electrons found in an atom?
On the outer shells
How can you work out the number of protons in the atom of a named element (e.g carbon)?
Use the atomic/proton number in the periodic table.
This is the small number.
How can you work out the number of electrons in the atom of a named element (e.g carbon)?
Use the atomic/proton number in the periodic table.
This is the small number.
The number of electrons is always the same as the number of protons.
How can you work out the number of neutrons in an atom of a named element (e.g carbon)?
Mass number - atomic/proton number
The mass number is protons plus neutrons, so if you take the number of protons away from the mass number you are left with the number of neutrons.
Which of the following decides what element an atom is:
- The number of electrons
- The number of protons
- The number of neutrons
- The atomic mass
The number of protons.
For example, if an atom has 6 protons, it must be carbon.
What did scientists think atoms were like before electrons were discovered?
They thought that they were tiny spheres (balls) that could not be divided (broken into smaller pieces).
Who discovered electrons and what was his model of the atom called?
Thomson.
The Plum Pudding Model
What did Thompson (Plum Pudding Model) suggest the atom was like?
A ball of positive charge with negative electrons scattered in it.
Rutherford realised that the plum pudding model was wrong.
What was Rutherfords model of the atom like?
What did he call his model of the atom?
Rutherford thought the atom was made of a tiny positvely charged nucleus, surrounded by scattered eletrons.
He called it: The nuclear model
- What did Rutherford do to test the structure of the atom?
- What were his results and what did they show?
3. Extension: What had Rutherford expected to happen (if the Plum Pudding model was correct)?
- Rutherford fired positively charged alpha particles at a thin sheet of gold.
2a. Most of the alpha particles went straight through the gold sheet: This showed that the atom was mainly empty space.
2b. Some of the alpha particles were deflected, and a small number were deflected backwards: This suggested that the positive charge in the atom was focussed in a tiny area at the centre of the atom (the nucleus). - Extension: Rutherford thought that all the alpha particles would pass straight through.
How did Bohr improve Rutherford’s nuclear model of the atom?
Bohr realised that electrons orbit the nucleus on shells.
After Bohr had realised that the electrons were on shells, Rutherford and Chadwick made further discoveries about the structure of the nucleus. What did they discover?
Protons were discovered: Rutherford realised that the nucleus could be divided into smaller positive particles.
Neutrons were discovered (20 years later): Chadwick showed that there were neutral particles in the nucleus.