Chemistry

• what is an element?

  Made up of one type of atom
• What is a compound?


  A compound is a substance composed of two or more elements chemically bonded together.
• how Many elements are in the periodic table?

  118
• What is the state symbol for a solid?

  (S)
• What is the state symbol for a liquid?

  (l)
• What is the state symbol for an aqueous solution?

  (aq)
• What is the state symbol for a gas?

  (G)
• What is the law of conservation of mass?

  No atoms can be created or destroyed during a chemical reaction
• What are the three processes that can separate a mixture?

  Filtration, distillation, and Crystallisation
• in Fractional distillation, which liquid is collected first?

  the liquid with the lowest boiling point
• How do substances separate in chromatograph?

  some compounds are more soluble than others in a solvent
• What is the order of history of the atom?


  Greeks, dalton, thomson, geiger and marsden, Bohr and Chadwick
• What were the order of discovery of subatomic particle?

  Electron, Proton, Neutron
• What is an ion?

  A charged atom
• What is an isotope?

  An isotope is a variant of an element that has the same number of protons but a different number of neutrons in its nucleus.
• What is the energy shell structure?

  2,8,8
• What are the electrons in an atom arranged in?

  Energy levels or shells.
• Why did Mendeleev leave gaps?

  Predicted elements, undiscovered elements
• How were the elements arranged in the early periodic table?

  By increasing atomic mass.
• why do elements in a group have similar chemical properties?

  Because they have the same number of electrons On outer shell
• Why are noble gases so unreactive?

  Full outer electron shell.
• What are the group 1?

  Alkali metals
• Why are alkali metals stored in oil?


  Very reactive
• What happens to the boiling point as you go down group 1?

  Decrease
• does the reactivity increase or decrease going down group 1?

  Increase
• What group are halogens?

  7
• Why do halogens have low melting and boiling points?

  Weak intermolecular forces
• What does electrostatic attraction depend on?

  Charge and distance Between atoms
• What are the three states of matter?

  The three states of matter are solid, liquid, and gas.
• which states contain particles in a random arrangement?

  Gas
• Why do substances have different melting points?

  Intermolecular forces
• What happens when a liquid turns to a gas?

  Evaporation
• What happens when a gas turns to a solid?

  Sublimation
• What happens when a gas turns to a liquid?

  Condensation
• What happens when two nonmetals react?


  Forms a covalent bond
• What happens when a metal and a non-metal react?

  Ionic bonding
• how can you show an electron shell?

  Dot and Cross diagrams
• What is formed from ionic bonding?

  A giant structure or giant lattice
• How are ionic compounds held together?

  Electrostatic forces
• Why do ionic solids have high melting points?

  Strong electrostatic forces