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Particles and atomic structures (separating mixtures ((solvent (The…
Particles and atomic structures
Atomic Structure
Molecule a group of atoms bonded together
Atom An atom consists of a central nucleus that is usually surrounded by one or more electrons
Atomic number the number of protons found in the nucleus.Protons have a positive charge Neutrons have no charge Electrons have a negative charge
Relative mass The ratio of the average mass of atoms of an element compared to the mass of a carbon-12 atom. to calculate the relative mass Multiply each percentage by the mass number. Add and then divide by 100%.
atoms are the smallest particle that can exist on their own
An atom is the smallest amount of a substance that can take part in a chemical reaction.
Elements are arranged in a periodic table in order of increasing atomic number. Elements with alike properties are in the same column (group), and elements with the same number of electron shells are in the same row (period).
for example if you have an element on the third row down in group seven: it will have three shell and 7 electrons on its outer shell.
isotopes same number of protons different number of neutrons.Atoms of the same element (same atomic number) different mass number.The mass number is
Particles
Gas
Gas particles move freely in all directions at high speeds
Condensing when a gas becomes a liquid if the gas is cooled down. They come close together and bonds form between them energy is released
solid
particles in a solid are more compact than a liquid or gas. the particles in a solid vibrate and the particles have less energy than the particles of a liquid of gas
resistance to changes of shape or total space occupied. For example unlike a liquid because it does not change shape in a container.
melting point, the temperature at which the solid melts to become a liquid. when thermal energy increases the particles in a solid vibrate so fast they break free from their positions becoming a liquid
liquid
he particles of a liquid are able to move past each other flow easy and take the shape of a container
Evaporation when a liquid becomes a gas . When boiling a liquid the liquid is heated the particles are given more energy and vibrate more quickly causing the most active particles to escape the liquid. Liquids evaporate faster when heated up for more particles are given the energy to break away
Freezing when a liquid becomes a solid.
the molecules of a liquid slow down (and decrease in energy) so their attractions cause them to arrange themselves into positions as a solid.
Difference between boiling and evaporation. Evaporation occurs at any temperature and is a slow process and takes place only on the surface. Boiling is a fast process that takes place throughout the liquid the temperature is fixed and thermal energy is supplied by a heat source.
All matter is made of up particles
Changing states
Freezing
decrease in energy
Melting
increase in energy
Condensing
decrease in energy
Boiling
increase in energy
Diffusion of gases
Example of gases diffusing. In a experiment two pieces of cotton wool are placed on opposite end of a glass tube the tube is sealed. On one end the cotton is soaked in ammonia solution the other cotton wool is soaked in concentrated hydrochloric acid.A ring (where the two gases meet) usually forms nearer to the hydrochloric acid because it diffuses more slowly than ammonia this is because hydrochloric acid is almost twice the molecular weight of ammonia and the rate of diffusion is corresponding to the molecular mass of the gas.
dilution of colored solutions from and area of high concentration to any area of low concentration. If the solute is coloured then the solution will have a colour. if the solute is white then the solution is colourless
Diffusion is faster at higher temperatures because the gas molecules have greater kinetic energy
Elements Compounds Mixtures
Elements
Any substance that contains only 1 type of atom. Cannot be broken down.
Mixtures
Made up of 2 or more different elements/compounds. Can be separated.
Compounds
Atoms of different elements can join together in chemical reactions to form compounds The properties of compounds are commonly much different from the properties of the elements they contain. Can be broken down.
separating mixtures
Simple distillation
Separating a solute or solvent from a solution two liquids with different boiling points can be separated. As the liquid being produced is heated, the vapors that form will be highest in the part of the mixture that boils at the lowest temperature then what rises condenses and liquid is collected.
crystallization
Used to separate a dissolved solute from a solvent. Example separating dissolved salt from water
filtration
Used to separate a solid from a liquid
paper chromatography
Rf value Rf = distance moved by the compound ÷ distance moved by the solvent
The Rf value of a particular compound is always the same different compounds can have the same Rf value for a particular solvent
separates several solutes dissolved in a solvent travels different distances on the paper. Example analyzing food colouring separate out mixtures of coloured dyes.Chromatography is used to separate mixtures of substances into their components.
Fractional distillation
separation of a liquid mixture into fractions differing in boiling point
Fractional distillation is mostly the same as simple distillation however the fractionating column is placed between the boiling flask and the condenser.
solvent
The substance in which the solute is dissolved is called a solvent.
solute
The substance which is dissolved is called a solute.
solution
A solution in chemistry is a mixture of two or more substances.
saturated solution
in a saturated solution no more of the solute can be dissolved in the solvent
solubility curves
solubility is measured by figuring out the maximum mass of a solute that can be mixed with and became part of a liquid (dissolve) in 100 g of a solvent at a given temperature.this is plotted between the temperature and solubility of a particular solute in an solubility curve.
