Chemistry Exam Revision

Separating Techniques:

• Filtration: Used to separate solids from liquids or gases using a filter. For instance, in water purification, a filter can remove impurities from water.

• Evaporation: A process that separates a soluble solid from a liquid by heating the solution until the liquid turns into vapor, leaving the solid behind. This technique is often used in salt production from seawater.

• Distillation: Separates substances based on differences in boiling points.

• Chromatography: A method used to separate mixtures based on the movement of different components through a medium.

• Centrifugation: Utilizes centrifugal force to separate substances of different densities, commonly used in laboratories for separating blood components.

• Decantation: Involves pouring off a liquid to leave behind solid sediments or another liquid, often used when separating liquids of different densities.

States of Matter:

• Solid: Has a definite shape and volume. Particles are closely packed together and vibrate in place.

• Liquid: Has a definite volume but takes the shape of its container. Particles are close together but can move past one another.

• Gas: Has no definite shape or volume. Particles are far apart and move freely, filling the available space.

• Plasma: A state of matter consisting of ionized gas with free-moving ions and electrons, typically found at high temperatures, such as in stars, including the sun.

Density is a physical property defined as mass per unit volume. It indicates how much matter is contained in a given volume and can be calculated using the formula:

Density = Mass / Volume.

In the context of separating techniques such as centrifugation, density plays a crucial role as it allows for the separation of substances based on their different densities.

Homogenous mixtures has the same uniform appearance and composition throughout.

Heterogeneous mixtures consists of visibly different substances or different states of matter.

Pure substances are actually quite rare and is often difficult to find in nature.  A pure substance is made up of only one type of matter.

Even substances that you think are pure, like rain water or clean air, are actually mixtures of different chemical compounds.

An impure substance is made up of different particle types and is just another name for a mixture!

It's often difficult to recognize a pure substance or an impure substance just by looking at them. Many mixtures have a uniform appearance, meaning that any part of them looks the same as any other part. It might seem as though there's just one type of particle because the different components are so well mixed.

A solution is a mixture in which the particles of the components are so small that they're invisible, even under powerful microscopes. The particles don't reflect light, allowing it to pass straight through a solution without being scattered. This means solutions are transparent, or see-through. They can still be coloured however.

Separating Techniques:

• Filtration: Used to separate solids from liquids or gases using a filter. For instance, in water purification, a filter can remove impurities from water.

• Evaporation: A process that separates a soluble solid from a liquid by heating the solution until the liquid turns into vapor, leaving the solid behind. This technique is often used in salt production from seawater.

• Distillation: Separates substances based on differences in boiling points.

• Chromatography: A method used to separate mixtures based on the movement of different components through a medium.

• Centrifugation: Utilizes centrifugal force to separate substances of different densities, commonly used in laboratories for separating blood components.

• Decantation: Involves pouring off a liquid to leave behind solid sediments or another liquid, often used when separating liquids of different densities.

States of Matter:

• Solid: Has a definite shape and volume. Particles are closely packed together and vibrate in place.

• Liquid: Has a definite volume but takes the shape of its container. Particles are close together but can move past one another.

• Gas: Has no definite shape or volume. Particles are far apart and move freely, filling the available space.

• Plasma: A state of matter consisting of ionized gas with free-moving ions and electrons, typically found at high temperatures, such as in stars, including the sun.

Density is a physical property defined as mass per unit volume. It indicates how much matter is contained in a given volume and can be calculated using the formula:

Density = Mass / Volume.

In the context of separating techniques such as centrifugation, density plays a crucial role as it allows for the separation of substances based on their different densities.

Homogenous mixtures has the same uniform appearance and composition throughout.

Heterogeneous mixtures consists of visibly different substances or different states of matter.

Pure substances are actually quite rare and is often difficult to find in nature.  A pure substance is made up of only one type of matter.

Even substances that you think are pure, like rain water or clean air, are actually mixtures of different chemical compounds.

An impure substance is made up of different particle types and is just another name for a mixture!

It's often difficult to recognize a pure substance or an impure substance just by looking at them. Many mixtures have a uniform appearance, meaning that any part of them looks the same as any other part. It might seem as though there's just one type of particle because the different components are so well mixed.

A solution is a mixture in which the particles of the components are so small that they're invisible, even under powerful microscopes. The particles don't reflect light, allowing it to pass straight through a solution without being scattered. This means solutions are transparent, or see-through. They can still be coloured however.

Separating Techniques:

• Filtration: Used to separate solids from liquids or gases using a filter. For instance, in water purification, a filter can remove impurities from water.

• Evaporation: A process that separates a soluble solid from a liquid by heating the solution until the liquid turns into vapor, leaving the solid behind. This technique is often used in salt production from seawater.

• Distillation: Separates substances based on differences in boiling points.

• Chromatography: A method used to separate mixtures based on the movement of different components through a medium.

• Centrifugation: Utilizes centrifugal force to separate substances of different densities, commonly used in laboratories for separating blood components.

• Decantation: Involves pouring off a liquid to leave behind solid sediments or another liquid, often used when separating liquids of different densities.

States of Matter:

• Solid: Has a definite shape and volume. Particles are closely packed together and vibrate in place.

• Liquid: Has a definite volume but takes the shape of its container. Particles are close together but can move past one another.

• Gas: Has no definite shape or volume. Particles are far apart and move freely, filling the available space.

• Plasma: A state of matter consisting of ionized gas with free-moving ions and electrons, typically found at high temperatures, such as in stars, including the sun.

Density is a physical property defined as mass per unit volume. It indicates how much matter is contained in a given volume and can be calculated using the formula:

Density = Mass / Volume.

In the context of separating techniques such as centrifugation, density plays a crucial role as it allows for the separation of substances based on their different densities.

Homogenous mixtures has the same uniform appearance and composition throughout.

Heterogeneous mixtures consists of visibly different substances or different states of matter.

Pure substances are actually quite rare and is often difficult to find in nature.  A pure substance is made up of only one type of matter.

Even substances that you think are pure, like rain water or clean air, are actually mixtures of different chemical compounds.

An impure substance is made up of different particle types and is just another name for a mixture!

It's often difficult to recognize a pure substance or an impure substance just by looking at them. Many mixtures have a uniform appearance, meaning that any part of them looks the same as any other part. It might seem as though there's just one type of particle because the different components are so well mixed.

A solution is a mixture in which the particles of the components are so small that they're invisible, even under powerful microscopes. The particles don't reflect light, allowing it to pass straight through a solution without being scattered. This means solutions are transparent, or see-through. They can still be coloured however.

Concentration refers to the amount of solute dissolved into a solvent.  Cordial from the shop is said to be concentrated – lots of sugar, colour and flavouring dissolved in a fixed volume of water.  We dilute this concentrate by adding water.

A solution with little dissolved solute has a low concentration. It is called a dilute solution.

Tap water is not pure. It has tiny amounts of salt and other minerals dissolved in it.   These salts and minerals are solutes, present in such small amounts that they can’t be tasted. Tap water is a dilute

A suspension is a mixture with two features:   Particles of one of the components are suspended, or "held up", in the other component.

Unlike a solution, the particles of the solute and solvent are not tiny. Rather, the particles of the solute are large enough that they can be seen floating in the solvent. Suspensions are made of two different phases of matter mixed together. It can be a solid mixed into a liquid, a gas mixed into a liquid, and any other combination of two phases.

A shaking, stirring, or flowing motion is required to keep the particles suspended. When the motion stops the components of the mixture separate out from each other.

A colloid is a mixture in which the particles are small enough that they stay suspended even when the mixture is left to stand.

In colloids the substances do notseparate. So they have the first feature of a suspension but not the second.

• that an atom consists of protons, neutrons, electrons and electron shells.

• know that the atomic number equals the number of protons and the atomic mass is the number of protons plus neutrons. 

• to read the periodic table and from that draw the basic structure of the atom including electron shells of any of the first 20 elements.