Atomic Structure (Edexcel IGCSE Chemistry)

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  • What is the mass and charge of a proton?

    A proton has a relative mass of 1 and a charge of +1.

  • True or False?

    All atoms of the same element have the same number of protons.

    True.

    All atoms of the same element have the same number of protons.

  • What is the mass and charge of an electron?

    An electron has a negligible mass and a charge of -1.

  • Define atomic number.

    Atomic number is the number of protons in the nucleus of an atom.

  • What information does the mass number give?

    The mass number is the total number of protons and neutrons in the nucleus of an atom.

  • What is an isotope?

    An isotope is an atom of the same element with:

    • A different number of neutrons and hence, a different mass number.

    • The same number of protons (and electrons).

  • Which subatomic particles are in the nucleus of an atom?

    The subatomic particles in the nucleus of an atom are protons and neutrons.

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

    To calculate the number of neutrons in an atom:

    • Number of neutrons = mass number - atomic number

      OR

    • Number of neutrons = mass number - number of protons

  • What is a molecule?

    A molecule is a group of two or more atoms held together by chemical bonds.

  • True or False?

    Atoms are made of subatomic particles.

    True.

    Atoms are made of subatomic particles including protons, neutrons, and electrons.

  • Define relative atomic mass.

    Relative atomic mass is:

    • The ratio of the average mass of atoms of an element to 1/12 of the mass of an atom of carbon-12

      OR

    • The average mass of an atom compared to 1/12 of the mass of an atom of carbon-12

  • Which subatomic particle has a mass of 1 and a charge of 0?

    The subatomic particle with a mass of 1 and a charge of 0 is the neutron.

  • How do you determine the number of electrons in an atom?

    The number of electrons in an atom is the same as the number of protons / the atomic number.

  • Calculate the number of protons, neutrons and electrons in an atom of Al presubscript 13 presuperscript 27.

    The number of protons, neutrons and electrons in an atom of Al presubscript 13 presuperscript 27 are:

    • Protons = 13

    • Neutrons = 27 - 13 = 14

    • Electrons = 13

  • State two pieces of information required to calculate the relative atomic mass of an element.

    Two pieces of information required to calculate the relative atomic mass of an element are:

    • The mass numbers of each isotope.

    • The (relative / percentage) abundances of each isotope.

  • State the equation for Ar in terms of the percentage abundance and mass of isotopes A and B.

    The equation for calculating relative atomic mass in terms of the percentage abundance and mass of isotopes A and B is:

    fraction numerator left parenthesis percent sign space of space isotope space straight A space cross times space mass space of space isotope space straight A right parenthesis space plus space left parenthesis percent sign space of space isotope space straight B space cross times space mass space of space isotope space straight B right parenthesis over denominator 100 end fraction

  • True or False?

    The relative atomic mass of an element can be calculated using the atomic numbers and relative abundances of all its isotopes.

    False.

    The relative atomic mass of an element is calculated using the mass numbers and relative abundances of all its isotopes.

  • In terms of isotopes, what is abundance?

    In terms of isotopes, abundance is the amount of each isotope present in a sample of an element.

  • Which of the following are isotopes?

    straight C presubscript 6 presuperscript 13 straight C presubscript 6 presuperscript 14 straight N presubscript 7 presuperscript 14

    The isotopes are straight C presubscript 6 presuperscript 13 and straight C presubscript 6 presuperscript 14.

    straight N presubscript 7 presuperscript 14 is not an isotope because it is a different element (nitrogen not carbon).

  • True or False?

    Relative atomic mass is calculated by adding the mass numbers of all isotopes.

    False.

    Relative atomic mass is calculated by:

    • Multiplying the abundance of each isotope by its mass

    • Adding these numbers together

    • Then, dividing this value by the total abundance.

  • How can you recognise isotopes from their chemical symbol?

    Isotopes have the same symbol and same atomic numbers but different mass numbers.

  • After calculating the Ar, how would you identify an element?

    After calculating the Ar, you would identify an element by looking for the value on the Periodic Table.

    For example, Ar = 23. On the Periodic Table, the element with an Ar of 23 is sodium.

  • Calculate the relative atomic mass of an element using this information about its isotopes:

    • Isotope 1: Mass = 71, abundance = 39%

    • Isotope 2: Mass = 69, abundance = 61%

    The relative atomic mass of the element is:

    fraction numerator open parentheses 71 cross times 39 close parentheses plus open parentheses 69 cross times 61 close parentheses over denominator 100 end fraction = 69.8 or 70