1 - Atomic Structure Flashcards
What are the elements in Group 1?
Alkali metals
What are the elements in Group 2?
Alkaline earth metals
What are the elements in the Middle section?
Transition metals
What are the elements along the Staircase?
Metalloids
What are the elements in Group 7?
Halogens
What are the elements in Group 8?
Noble gases
What is the law of the conservation of mass?
The total mass of products formed in a reaction is equal to the total mass of the reactants.
What are the features of a compound?
- fixed ratio
- joined & separated by chemical reactions
- have chemical bonds between atoms
What are the features of a mixture?
- no fixed composition
- created & separated by physical means
- no chemical bonds between atoms
What does filtration separate?
Insoluble substances from soluble ones.
What does crystallisation separate?
A pure sample of salt from a salt solution by heating & evaporation.
What does distillation separate?
A solvent from a solute by heating and evaporating off the liquid to be condensed.
What are miscible and immiscible liquids?
Miscible liquids dissolve in eachother and mix completely, whereas immiscible liquids form separate layers & settle over eachother.
How can you separate miscible liquids?
Evaporate and condense the liquid with a lower boiling point first.
What is fractional distillation?
When liquids have similar boiling points, you use a fractionating column to pass vapours between the glass beads. The substance with a higher boiling point will condense at the bottom and drip back down & the substance with a lower boiling point will continue to rise.
How can you test if an ethanol and water mixture has been fully distilled?
Apply a lighted splint to the mixtures - ethanol is flammable except when mixed with excess water.
What is paper chromatography?
Paper chromatography separates mixtures of substances dissolved in a solvent as they move up the chromatography paper.
What is the history of the atom?
- John Dalton - atoms were tiny hard spheres that could not be divided or split
- J.J. Thomson discovered the electron when applying high voltages to gases at low pressures - beams of particles were attracted to positive charge = they were negatively charged. He proposed that electrons were embedded in positive mass.
- Geiger & Marsden - Alpha particles experiment. Discovered that electrons orbit the nucleus, containing protons.
- Niels Bohr - Discovered energy levels/shells on atoms.
- Evidence of the neutron was explained by ‘missing mass’
What is the atomic number?
No. of protons (also no. of electrons)
What is the mass number?
No. of protons + neutrons
What are isotopes?
Atoms of the same element with different numbers of neutrons.
Why are the physical properties of isotopes different but the chemical properties are the same?
Isotopes have different physical properties such as density or radioactivity however, their chemical properties stay the same because their reactions with other elements depend on the electronic structure of their outer shell.
