States of matter are the different forms we find elements, compounds and mixtures in the periodic table as solids liquids and gases.
Not all elements have the same state, the state is the way they exist in nature. This can be as a solid, liquid or a gas. This is because elements all have different atoms that can interact in different ways meaning they have different melting and boiling points, the temperatures at which they change states.
Solids are tightly packed with their atoms having a regular arrangement. Regular is usually defined as being in a lattice like structure where atoms are the same size and in layers. Solids are very strong usually and will resist pressure and forces applied to them. However some solids may be brittle and weak depending on their bonding. Property wise many solids like metal are good electrical conductors due to the closely packed atoms and also good conductors of heat as vibrations can easily travel through them. Due to the atoms in a solid being held in a fixed position, solids often have a defined volume and shape/structure.
Liquids are less ordered. The particles in a liquid often move around each other freely, because of this liquids often take the shape of their container and can be poured as the weak attractions between the atoms mean they can flow. Liquids also often have lower boiling points than solids as less energy is needed to overcome the forces between the particles meaning liquids will readily turn into gases. Liquids are often less dense than solids as they are less closely packed with space between the molecules. With a few exceptions such as the alkali metals which will readily float on water.
Gaseous atoms are much more spread out than liquids. In a similar way they are free to move and less densely packed but the atoms are spread over much greater distances. Like liquids gases will often take the shape of the container they are placed in and will exhibit pressure on the surfaces of such a container. Gaseous particles can flow due to their free movement and can also be squashed by reducing the volume of the container it is in. Gas particles often are poor conductors of heat and electricity due to the wide spaces between the atoms. They also have very low boiling and melting points requiring very very low temperature to turn them into liquids.
In the periodic table there are a number of elements in the actinide and lanthanide series that have unknown states. This is often because due to the radioactivity of these elements they decay very quickly breaking down into smaller elements and releasing alpha, beta and gamma radiation. In the case of many of these atoms also not enough atoms have been created to witness their state of matter. For many of the larger elements in the periodic table we can only hypothesise their state using patterns in the groups they exist in as not enough atoms have been created that last long enough for the synthetic elements to be studied.
Packed is a term to describe when atoms are close to each other and there is little space between the atoms
Regular/ordered are terms to describe how atoms are arranged and laid out usually meaning they are in layers, the same size and in neat rows
A lattice is a 3D layout of atoms of similar sizes next to each other. They are tightly packed and in neat rows and columns
Brittle is used to describe a physical property where layers of atoms when moved across each other will break apart. Commonly in ionic lattices as the ions repel each other
An electrical conductor has the ability to conduct electricity and carry an electrical current usually when electrons or ions can move
Vibrations happen when movement energy in atoms causes small movements of atoms from side to side causing the energy to move through more atoms
A fixed position means that an atom does not move unless forced
Volume is a measure of 3 dimensional space that a substance can occupy measured in cm3. Volume is used to measure gases, solids, and liquids.
Attractions are when atoms are close to each other and they are joined by a weak force this is known as an attraction
Boiling point is the temperature at which a liquid turns into a gas. The particles have enough internal energy to overcome the bonds in the liquid.
Melting point is the temperature at which a solid turns into a liquid. The temperature when atoms have enough energy to over come their bonds and turn into a liquid.
Temperature is a measure of heat energy this is the amount of movement energy in a substance that can be measured using a thermometer
Radioactivity is a property of some elements where the nucleus breaks down and turns into smaller parts to release energy
Alpha particles are made of 2 protons and 2 neutrons released from a nucleus when it breaks apart
Beta particles are made of an electron released from a nucleus when it breaks apart
Gamma particles that are made of waves released from a nucleus when it breaks apart
To hypothesise is to think about and using knowledge to predict what will happen