1.1 Atomic structure and PT

• What is an atom?


  An atom is the smallest part of an element that can exist.
• What is an element?


  An element is a substance of only one type of atom.
• How can elements be classified based on their properties?


  Elements can be classified into metals and non-metals.
• What is a compound?


  A compound is two or more elements combined chemically in fixed proportions.
• What are the methods through which mixtures can be separated?

  • Filtration
  • Crystallisation
  • Simple distillation
  • Fractional distillation
  • Chromatography
  • These methods do not involve chemical reactions.
• What is simple distillation used for?


  Simple distillation is used to separate liquid from a solution.
• How does simple distillation work?


  The liquid boils off and condenses in the condenser, with the thermometer reading the boiling point of the pure liquid.
• What is the difference between evaporation and crystallisation?


  Evaporation removes all the solvent, while crystallisation removes some solvent to form a saturated solution.
• What happens during crystallisation?


  The solution is cooled after removing some solvent, causing the solid to crystallise as it becomes less soluble at lower temperatures.
• What is fractional distillation used for?

  Fractional distillation is used to separate a mixture of liquids with different boiling points.
• How does fractional distillation work?


  It uses a fractionating column to separate compounds based on their boiling points.
• What is the role of the fractionating column in fractional distillation?


  The fractionating column contains glass beads and helps to separate the compounds by allowing them to condense at different heights.
• What is filtration used for?

  Filtration is used to separate an insoluble solid suspended in a liquid.
• How does filtration work?


  The insoluble solid gets caught in the filter paper, while the filtrate passes through.
• What is chromatography used for?


  Chromatography is used to separate a mixture of substances dissolved in a solvent.
• How does paper chromatography work?


  A spot containing a mixture is placed on paper, which is then immersed in a solvent, causing the mixture to separate into components.
• What is a separating funnel?


  A separatory funnel is an apparatus for separating immiscible liquids.
• How do immiscible liquids behave in a separatory funnel?


  They form two distinct layers based on their different densities.
• What is the plum-pudding model of the atom?


  The plum-pudding model describes the atom as a ball of positive charge with negative electrons embedded in it.
• What does the nuclear model of the atom suggest?


  The nuclear model suggests that electrons orbit the nucleus at specific distances (shells).
• What discovery did the alpha scattering experiments lead to?


  They led to the discovery of the nuclear model of the atom.
• What are the smaller positive particles found in the nucleus called?

  Protons.
• What did the work of James Chadwick provide evidence for?


  It provided evidence for the existence of neutrons in the nucleus.
• Describe the structure of an atom.

  The atom has a small central nucleus made up of protons and neutrons, around which there are electrons.
• What are the relative masses of protons, neutrons, and electrons?


  Masses: 1, 1, very small; Charges: 1, 0, -1 (respectively).
• Why are atoms electrically neutral?


  Atoms are electrically neutral because they have the same number of electrons and protons.
• What is the radius of an atom?


  0.1 nm.
• What is the atomic number?


  The atomic number is the number of protons in the nucleus.
• What particle do atoms of the same element have the same number of?


  Protons.
• Where is the majority of an atom's mass located?

  The majority of an atom's mass is located in the nucleus.
• What is the mass number?


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


  An isotope is an atom of the same element that has a different number of neutrons.
• Do isotopes of a certain element have the same chemical properties?


  Yes, they have the same chemical properties as they have the same electronic structure.
• What is the relative atomic mass?


  The relative atomic mass is the average mass value that takes the mass and abundance of isotopes into account.
• What are ions?


  Ions are charged particles formed when atoms lose or gain electrons.
• What happens when a metal reacts with a non-metal?

  An ionic compound is formed, made of positive and negative ions.
• What happens when a non-metal reacts with a non-metal?


  A molecular compound is formed containing covalently bonded atoms.
• What are the columns of the periodic table called?

  Groups.
• What are the rows of the periodic table called?

  Periods.
• Are elements in the same group similar or different?


  They may have similar chemical properties due to having the same number of outer shell electrons.