C2 - The Periodic Table Flashcards
What is a compound?
Two or more elements which are chemically bonded.
What is a mixture?
Two or more substances which are 𝗡𝗢𝗧 chemically bonded.
List the methods of separating mixtures
Filtration, Evaporation, Distillation, Fractional distillation, Crystallisation, Chromatography. As these do not include chemical reactions and no new substances are made.
List the names of scientists who helped develop the model of the atom (in chronological order)
John Dalton, J.J. Thomson, Ernest Rutherford, Niels Bohr, James Chadwick
What did John Dalton do?
Developed the Solid Sphere Model: Atoms are indivisible, indestructible particles, each element having its own kind of atom.
What did J.J Thomson do?
Proposed the Plum Pudding Model: Atoms are composed of negatively charged electrons embedded in a positively charged sphere.
What did Ernest Rutherford do?
Developed the Nuclear Model: Discovered the nucleus, a dense positive center, with electrons orbiting around it.
What did Niels Bohr do?
Proposed the Bohr Model: Electrons orbit the nucleus in fixed energy levels or shells.
What did James Chadwick do?
Discovered the neutron, completing the understanding of the atomic nucleus as containing both protons and neutrons.
What are columns and rows called in the periodic table?
Columns - Groups
Rows - Periods
What are group 1 elements called?
Alkali metals
What are group 2 elements called?
Alkali earth metals
What are group 7 elements called?
Halogens
What are group 8 elements called?
Noble gases
List the properties of alkali metals
- very reactive
- reactivity increases going down the group
- low density
- low melting/boiling point
- soft
- shiny when cut
List the properties of halogens
- very reactive
- reactivity decreases going down the group
List the properties of noble gases
- inert (unreactive)
- very low melting/boiling point
What is observed when an alkali metal is reacted with water?
- fizzes
- floats on the surface
- moves around on the surface
product of the reaction between an alkali metal and water
metal hydroxide + hydrogen
What is the colour of each aqueous solution:
- Cl2
- Br2
- I2
- Cl2 - green
- Br2 - yellow
- I2 - brown
When potassium is reacted with water, what colour does it burn?
Lilac
Why are alkali metals reactive?
They have 1 electron in their outer shell, meaning they can lose this electron easily.
Why does reactivity increase going down the group with alkali metals?
The electrostatic force of attraction between the nucleus and outer shell becomes weaker as the element becomes larger, therefore losing the outer electron becomes easier.
Why are halogens reactive?
They have 7 electrons in their outer shell, meaning they can gain an electron easily.
Why does reactivity increase going down the group with halogens?
The electrostatic force of attraction between the nucleus and an attracted electron becomes weaker as the element becomes larger, therefore gaining an electron becomes harder.
What are the elements in the middle of the periodic table called?
transition metals
