FLASH - GCSE Chemistry 5.1.1 - Atomic Structure Flashcards
What is an atom?
An atom is the smallest part of an element that can exist
What is an element?
An element is a substance of only one type of atom.
How are the elements listed and approximately how many are there?
They are listed in the periodic table; there are approximately 100.
Elements can be classified into two groups based on their
properties; what are these groups?
Metals and non-metals
Elements may combine through chemical reactions to
form new products; what are these new substances called?
Compounds
What is a compound?
Two or more elements combined chemically 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? Does it have the
same chemical properties as its
constituent materials?
A mixture consists of two or more elements or compounds not chemically combined together; it does have the same chemical properties
What are the methods through
which mixtures can be separated
(there are five)? Do these involve
chemical reactions?
Filtration, crystallisation, simple distillation, fractional distillation and 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. Contrary to evaporation, we get to keep the liquid
Describe and explain
crystallisation/evaporation
Evaporation is a technique for separation of a solid dissolved in a solvent from a solvent (e.g. salt from H2O).
The solution is heated until all the solvent evaporates; the solids stays in the vessel.
Crystallisation is similar, but we only remove some of the solvent by evaporation to form a saturated solution (the one where no more solid can be dissolved). Then, we cool down the solution. As we do it, the solid starts to crystallise, as it becomes less soluble at lower temperatures. The crystals can be collected and separated from the solvent via filtration.
Describe and explain
fractional distillation
Fractional distillation is a technique for separation of a mixture of liquids.
It works when liquids have different boiling points.
The apparatus is similar to the one of simple distillation apparatus, with the additional fractionating column placed on top of the heated flask.
The fractionating column contains glass beads. It helps to separate the compounds.In industry, mixtures are repeatedly condensed and vapourised. The column is hot at the bottom and cold at the top. The liquids will condense at different heights of the column
Describe and explain
filtration
Filtration is used to separate an insoluble solid is suspended in a liquid.
The insoluble solid (called a residue) gets caught in the filter paper, because the particles are too big to fit through the holes in the paper.
The filtrate is the substance that comes through the filter paper.
Apparatus: filter paper + funnel.
Describe and explain
chromatography
Chromatography is used to separate a mixture of substances dissolved in a solvent.
In paper chromatography, we place a piece of paper with a spot containing a mixture in a beaker with some solvent. The bottom of the paper has to be in contact with the solvent. The solvent level will slowly start to rise, thus separating the spot
(mixture) into few spots (components)
What is a separating funnel?
A separatory funnel is an apparatus for separating immiscible liquids.
Two immiscible liquids of different densities will form two distinct layers in the separatory funnel.
We can run off the bottom layer (the liquid with greater density) to a separate vessel
Describe the plum-pudding
model
The atom is a ball of positive charge with negative electron embedded in it
Describe the Bohr/nuclear
model and how it came
about
The nuclear model suggests that electrons orbit the nucleus at specific distances (shells) – it came about from the alpha scattering experiments
Later experiments led to the
discovery of smaller, positive
particles in the nucleus; what are
these particles called?
Protons
What did the work of James
Chadwick provide evidence
for?
The existence of neutrons in the nucleus
Describe the structure of an
atom
The atom has a small central nucleus (made up of protons and neutrons) around which there are electrons
State the relative masses and
relative charges of the proton,
neutron and electron
Masses: 1, 1, very small ; Charges: 1, 0 , -1 (respectively)
Explain why atoms are
electrically neutral
They have the same number of electrons and protons
What is the radius of an
atom?
0.1 nm
What is the radius of a nucleus and
what is it compared to that of the
atom?
1 x 10-14 m and 1/10000
What name is given to the
number of protons in the
nucleus?
Atomic number
Atoms of the same element have
the same number of which particle
in the nucleus?
Protons
Where is the majority of
mass of an atom?
The nucleus
What is the mass number?
The total number of protons and neutrons
How does one calculate the
number of neutrons using mass
number and atomic number?
Subtract the atomic number from the mass number
What is an isotope? Do isotopes
of a certain element have the same
chemical properties?
Atoms of the same element (same proton number) that have a different number of neutrons.
They have the same chemical properties as they have the same
electronic structure
What is the relative atomic
mass?
The average mass value which takes the mass and abundance of isotopes of an element into account, on a scale where the mass of 12C is 12
Give the electronic configurations of He (2), Be (4), F (9), Na (11), and Ca (20) to demonstrate how shells are occupied by electrons.
2
2,2
2,7
2,8,1
2,8,8,2
