Atomic Structure and the Periodic Table Flashcards
What is an atom?
The smallest part of an element that can exist.
What is an element?
A substance of only one type of atom.
What is a compound?
Two or more elements chemically combined in fixed proportions which can be represented by formulae.
Do compounds have the same properties as their constituent elements?
No, they have different properties.
What is a mixture?
A mixture has two or more elements or compounds not chemically combined together; It does have the same chemical properties.
What are the methods of Separation (5)
F Cr Sd Fd Chr
Filtration Crystallisation Simple Distillation Fractional Distillation Chromatography They do not involve chemical reactions.
Describe and explain simple distillation.
Simple distillation is used to separate liquid from a solution - The liquid boils off and condenses in the condenser. The thermometer will read the boiling point of the pure liquid. Opposite to evaporation, we keep the liquid.
Describe and explain Crystallisation / Evaporation.
Evaporation is a technique of separation of a solid dissolved in a solvent from a solvent. The solution is heated until the solvent evaporates and the solid stays in the vessel.
Crystallisation is similar, but we only remove some solvent by evaporation to form a SATURATED SOLUTION. Then we cool down the solution and the solid starts to crystallise as it becomes LESS SOLUBLE AS LOWER TEMPERATURES.. The crystals can be collected and separated from the solvent via filtration.
Describe and explain fractional distillation.
A technique for separation of a mixture of liquids into with different boiling points into fractions.
The mixture is evaporated and its vapours condense at different temperatures in the Fractionating column.
The fractionating column is placed on top of the heated flask and is hot at the bottom and cool at the top. This is so SUBSTANCES WITH HIGH BOILING POINTS CONDENSE AT THE BOTTOM and substances with LOWER BOILING POINTS CONDENSE AT THE TOP.
Describe and explain filtration.
Used to separate insoluble solid from a liquid.
The residue gets caught in the filter paper as the particles are too big to fit through the holes in the paper. The FILTRATE comes through the filter paper.
Describe and explain chromatography.
Used to separate a mixture of substances dissolved in a solvent.
In paper chromatography, we place paper with a spot containing a mixture in a beaker with a solvent. The bottom of the paper has to be in contact with the solvent.
The solvent level will rise and the spot will separate into few spots with other colours.
Describe the plum pudding model.
The atom is a ball of positive charge with negative electron embedded in it.
Describe the Bohr Model and how it come about.
How did the Bohr Model give evidence that lead to a change in the atomic model?
The model suggests that electrons orbit the nucleus in forms of shells - formed by alpha scattering experiments.
The results from the alpha particle scattering experiment led to the conclusion that the mass of an atom was concentrated at the nucleus and that the nucleus was charged.
What did James Chadwick discover?
The existence of neutrons in the nucleus.
Describe the structure of an atom.
Small central nucleus made of protons and neutrons which the nucleus is surrounded by electrons.
State the relative masses and relative charges of the proton, neutron and electron.
Proton:
Relative Mass 1
Relative Charge: 1
Neutron:
Relative Mass 1
Relative Charge 0
Electron:
Relative Mass is very small
Relative Charge -1
Explain why atoms are electrically neutral.
They have the same number of electrons and protons.
What is the radius of an atom?
0.1nm
Sodium has a Mass Number of 23 and an Atomic Number of 11.
What is Mass Number and Atomic Number?
Mass number is the total number of protons and neutrons.
Atomic Number is the total amount of protons.
What is an isotope?
Atoms of the same proton number but have a different number of neutrons.
They have the same chemical properties as their electronic structure is the same.
What are ions?
Ions are charged particles.
Compare the properties of metals and non-metals.
Metals have high boiling and melting point, can conduct heat and electricity, are shiny, are malleable, are very dense, and oxides are basic.
Non-metals have low boiling and melting point, cannot conduct heat or electricity except GRAPHITE, are dull, are brittle, not dense, and oxides are acidic.
Horizontal lines of Periodic Tables are … ?
Groups
Vertical lines of Periodic Tables are … ?
Periods
