Chemistry

• A colloid is a mixture where one substance is dispersed as small particles throughout another substance.
• Emulsion is where two immiscible liquids are dispersed in each other.
• Immiscible liquids are unable to mix with each other to form a homogeneous mixture.
• Miscible liquids are capable of mixing with each other to form a homogeneous mixture.
• Chromatography is used to separate molecules on the basis of difference in size,mass etc.
• An element consists of different kinds of atoms.
• A compound is made up of different kinds of atoms that have been chemically combined in a simple ration.
• A mixture is the combination of different elements and compounds that have not been chemically combined.
• Homogeneous mixtures are solutions with a uniform composition throughout and are evenly distributed at a molecular level.
• Heterogeneous mixtures are solutions that are not uniform throughout and unevenly distributed at a molecular level.are
• Adding impurities to solids can lower the melting points because they weaken the intermolecular forces, making them less stable; hence, it takes a lower temperature for the solid to melt.
• Kinetic theory of matter states that matter is made of small particles which is in random motion and has spaces between them.
• Boiling point is the temperature at which vapour pressure is equal to the external pressure of the liquid.
• Melting point is the temperature at which a solid turns into a liquid.
• Freezing point is the temperature at which a liquid turns into a solid.
• Vapour pressure is the measure of pressure exerted by a gas above a liquid in a sealed container.
• What are miscible liquids?

  Are liquids that can mix to form a homogeneous mixture.
• Isotopes are elements with the same number of protons and electrons but different number of neutrons.
• Electronic configuration is the distribution of electrons in the shells of atoms.
• Van der Waal's forces of attraction are weak intermolecular forces that attract neutral molecules to each other.
• Ionisation energy is the minimum energy that is needed to remove the most loosely bound electron from a gaseous atom or ion.
• Electronegativity is chemical property where atoms are able to attract electrons to itself.
• Electron affinity is the energy change (Kj/mol) of a neutral atom when an electron is added to form a negative ion.
• Across a period, the atomic radius decreases because, as protons and electrons are added, there is an increase in the nuclear charge. The increased nuclear charge pulls the electrons closer to the nucleus, making it smalller.
• Across a period, the ionisation energy increases because there is an increase in nuclear energy, which allows inner electrons to shield the outermost electrons from the path of nuclear charge(shielding effect).
• Across a period, electronegativity increases due to the increase in nuclear charge and decrease in atomic radius.
• Down the group, the atomic radius increases due to the addition of new shells which increases the distance and attraction between the nucleus and the outermost electrons.
• Down the group, the ionisation energy decreases because the attraction between the nucleus and the outermost electron is weak as the atomic radius increases, and the addition of new shells so it takes less energy for an electron to be removed.
• Down the group, the electronegativity decreases because the attraction between the nucleus and the valence electrons is weak, so the atom isn't able to attract electrons to itself.
• Metal bonding is the electrostatic force between the metal ions arranged in a lattice structure with a sea of free-floating electrons around them
• Ionic bonds are formed when a metal transfers electrons to a non-metal, which creates oppositely charged ions that attract each other.
• Ionic bonds have a high melting point because a lot of energy is needed to overcome the electrostatic force between them
• Covalent bonds are formed when non-metals share electrons, with each other.