Paper 1

• What does Dalton's model state about atoms?

  Atoms are solid spheres that cannot be divided
• What did JJ Thompson propose about the atom?

  Atoms are clouds of positive charge with electrons
• What experiment did Rutherford conduct?

  Alpha scattering experiment
• What did Rutherford's experiment reveal about atomic structure?

  Atoms have a central nucleus and are mostly empty space
• What is the electron shell model?

  Electrons orbit the nucleus at fixed distances
• What are protons?

  Positively charged particles in the nucleus
• What are neutrons?

  Neutral particles found in the nucleus
• What are electrons?

  Negatively charged particles orbiting the nucleus
• What is the radius of an atom?

  About $0.1 \text{ nm}$ or $1 \times 10^{-10} \text{ m}$
• What is the definition of an element?

  A substance made of only one type of atom
• How are elements represented?

  By chemical symbols starting with a capital letter
• What is a compound?

  A substance with two or more different elements combined
• How can compounds be separated?

  Only by chemical reactions
• What happens during a chemical reaction?

  New substances are formed with energy changes
• What is the word equation for water decomposition?

  Water → Hydrogen + Oxygen
• What is the symbol equation for water decomposition?

  $2H_2O \rightarrow 2H_2 +$$O_2$
• How do you balance a chemical equation?

  Ensure equal atoms on both sides of the arrow
• 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 an isotope?

  Atoms with the same protons but different neutrons
• What is an ion?

  A charged particle from gaining or losing electrons
• How do you represent a bromine ion with a charge?

  Br⁻ for a negative charge
• What is the maximum number of electrons in the first shell?

  2 electrons
• What is the maximum number of electrons in the second shell?

  8 electrons
• What is the maximum number of electrons in the third shell?

  8 electrons
• What is the mass number?

  The sum of protons and neutrons in an atom
• What is the atomic number?

  The number of protons in an atom
• How do you calculate the number of neutrons?

  Mass number minus atomic number
• How do you find the number of electrons in a neutral atom?

  It equals the number of protons
• How do you determine the number of electrons in a negative ion?

  Add one electron for each negative charge
• What is relative atomic mass?

  The average mass of atoms compared to carbon-12
• Why do some elements have non-integer relative atomic masses?

  Due to the presence of isotopes
• What is the formula to calculate the number of neutrons?

  Mass number minus number of protons
• How many neutrons are in an atom with mass number 80 and 35 protons?

  45 neutrons
• How do you determine the number of electrons in an ion?

  Protons plus or minus charge
• Why does a bromide ion (Br^-) have one more electron than protons?

  To achieve an overall negative charge
• What is the definition of relative atomic mass?

  Average mass compared to carbon-12
• Why are relative atomic masses not whole numbers?

  They are averages of different isotopes
• What is the relative atomic mass of chlorine?

  35.5