Atomiic Structure and the periodic table

• What are atoms the smallest part of?

  An element
• What does the chemical symbol Na represent?

  An atom of sodium
• How are compounds formed?

  By chemical reactions between elements
• What do chemical reactions involve?

  Formation of new substances and energy change
• How many elements are in a compound?

  Two or more
• How can compounds be represented?

  By formulae using chemical symbols
• What is the formula for hydrochloric acid?

  HCl
• How can compounds be separated into elements?

  Only by chemical reactions
• What is a mixture?

  Two or more substances not chemically combined
• What happens to the chemical properties of substances in a mixture?

  They remain unchanged
• Name one method to separate mixtures.

  Filtration
• What type of processes are used to separate mixtures?

  Physical processes
• What was the first model of the atom thought to be?

  Tiny spheres that could not be divided
• What did the discovery of the electron lead to?

  The plum pudding model of the atom
• What did the alpha particle scattering experiment conclude?

  The mass of an atom is concentrated in the nucleus
• What was aimed at the gold foil in the scattering experiment?

  A beam of alpha particles
• What happened to some alpha particles in the experiment?

  They emerged at different angles
• Why were alpha particles repelled in the experiment?

  Due to a small concentration of positive charge
• Who suggested that electrons orbit the nucleus?

  Neil Bohr
• What did later experiments reveal about the nucleus?

  It can be subdivided into smaller particles
• What are protons?

  Particles with a positive charge
• What is the atomic number?

  The number of protons in an atom
• Do all atoms of a particular element have the same number of protons?

  Yes
• What is the relative charge of a proton?

  +1
• What is the relative charge of a neutron?

  0
• What is the relative charge of an electron?

  -1
• What is the overall charge of an atom?

  0
• What does the mass number represent?

  The sum of protons and neutrons

  
• What are isotopes?

  Atoms of the same element with different neutrons
• How is relative atomic mass shown in the periodic table?

  As an average value considering isotopes
• How do you calculate the relative atomic mass of carbon with isotopes?

  Use the formula: ((isotope mass x abundance) ÷ 100)
• Where do electrons occupy in an atom?

  The lowest available energy levels
• What does the electronic structure of an atom indicate?

  How many electrons are in each shell
• What are the key differences between compounds and mixtures?

  • Compounds are chemically combined; mixtures are not.
  • Compounds have fixed proportions; mixtures do not.
  • Compounds can only be separated by chemical reactions; mixtures can be separated by physical processes.
• What are the historical developments in the model of the atom?

  1. Tiny spheres (indivisible)
  2. Plum pudding model (positive charge with electrons)
  3. Nuclear model (mass concentrated in nucleus)
  4. Bohr model (electrons orbiting nucleus)
  5. Discovery of protons and neutrons
• What is the significance of the alpha particle scattering experiment?

  • Demonstrated the existence of the nucleus.
  • Showed that mass is concentrated at the center.
  • Indicated that the nucleus is positively charged.
• What is the relationship between protons, neutrons, and electrons in an atom?

  • Protons: +1 charge
  • Neutrons: 0 charge
  • Electrons: -1 charge
  • An atom has equal numbers of protons and electrons, resulting in a neutral charge.
• How is relative atomic mass calculated using isotopes?

  • Average value based on abundance of isotopes.
  • Formula: ((isotope mass x abundance) + (isotope mass x abundance)) ÷ 100.
• How are elements arranged in the periodic table?

  By atomic (proton) number
• What is the significance of groups in the periodic table?

  Elements in groups have similar properties