atomic structure

• What is the basic structure of an atom?

  An atom consists of a central nucleus surrounded by electrons orbiting in rings (shells).
• What particles make up the nucleus of an atom?

  The nucleus is made up of protons and neutrons.
• What is the relative mass and charge of protons?

  Protons have a relative mass of 1 and a charge of +1.
• What is the relative mass and charge of neutrons?

  Neutrons have a relative mass of 1 and are neutral (charge of 0).
• What is the relative mass and charge of electrons?

  Electrons have a relative mass of 0 and a charge of -1.
• What happens when the number of protons equals the number of electrons in an atom?

  The atom is neutral.
• What are ions?

  Ions are atoms that have lost or gained electrons.
• What determines the identity of an element?

  The number of protons in an atom determines which element it is.
• What is the smallest element?

  The smallest element is hydrogen.
• What is the mass number of an atom?

  The mass number is the total number of protons and neutrons in the nucleus.
• What is an isotope?

  An isotope is a form of an element that has the same number of protons but a different number of neutrons.
• What is the notation for carbon-12?

  The notation for carbon-12 is $^{12}_{6}C$.
• What is the notation for carbon-13?

  The notation for carbon-13 is $^{13}_{6}C$.
• How do different isotopes of an element behave chemically?

  Different isotopes react the same way chemically.
• What is relative atomic mass?

  Relative atomic mass is the sum of (isotope abundance × isotope mass) divided by the sum of abundance of all isotopes.
• What is a molecule?

  A molecule is two or more atoms held together by chemical bonds.
• Can molecules contain different elements? Give an example.

  Yes, molecules can contain different elements, e.g., H₂O.
• What is a compound?

  A compound is two or more different elements held together by chemical bonds.
• How are compounds always found?

  Compounds are always found in the same proportions, e.g., H₂O, CO₂.
• What is a mixture?

  A mixture is two or more substances that are not chemically combined together.
• How can mixtures be separated?

  Mixtures can be easily separated using physical methods like filtration, crystallization, and distillation.
• What is the historical development of the atomic model?

  • 500 BC: Democritus proposed atomic theory.
  • 1800s: John Dalton described atoms as solid spheres.
  • 1897: JJ Thompson introduced the Plum Pudding Model.
  • 1909: Ernest Rutherford developed the Nuclear Model.
  • 1913: Niels Bohr proposed electron shells.
• What did Democritus contribute to atomic theory?

  Democritus proposed that everything is made up of tiny particles that can't be broken down further.
• What was John Dalton's model of the atom?

  John Dalton described atoms as solid spheres that make up different elements.
• What did JJ Thompson discover about the atom?

  JJ Thompson discovered that atoms must contain negatively charged particles (electrons).
• What experiment did Ernest Rutherford conduct, and what did he discover?

  Ernest Rutherford fired positively charged alpha particles at gold foil and discovered a compact nucleus with positive charge.
• What did Niels Bohr propose about electron arrangement?

  Niels Bohr proposed that electrons orbit the nucleus in shells to prevent the atom from collapsing.
• Who discovered neutrons and what are they?

  James Chadwick discovered neutrons, which are neutral particles in the nucleus.
• What is the density characteristic of group 1 metals?

  They are low density.
• How do group 1 metals react with water?

  They are reactive with water.
• Name three elements in group 1 metals.

  Lithium, sodium, potassium
• How many electrons do alkali metals have in their outer shell?

  One electron.
• What trend occurs in reactivity as you go down group 1?

  Reactivity increases down the group.
• Why does reactivity increase down group 1 metals?

  The outer electron is lost more easily.
• What happens to the melting and boiling points of alkali metals down the group?

  They decrease down the group.
• What type of compounds do alkali metals form with non-metals?

  Ionic compounds.
• Why do alkali metals readily form 1+ ions?

  They lose one outer electron easily.
• What is the appearance of ionic compounds produced by alkali metals?

  Generally white solids.
• What happens to ionic compounds of alkali metals in water?

  They dissolve to form colorless solutions.
• What is the reactivity characteristic of group 0 noble gases?

  They are very unreactive.