Understanding the Atom: Protons, Neutrons, and Electrons

Protons, Neutrons, and Electrons

Atomic Mass

  • Protons and neutrons have approximately the same mass.

  • Electrons possess significantly less mass compared to protons and neutrons.

  • The majority of an atom's mass is concentrated in the nucleus.

Elements and Protons

  • Each element is defined by a unique number of protons.

  • The atomic number of an element corresponds to the number of protons in one atom of that element.

  • In a neutral atom, the number of electrons equals the number of protons, ensuring that positive and negative charges are balanced, resulting in a net-neutral charge.

Neutrons and Isotopes

  • Isotopes are variants of an element that share the same number of protons but differ in the number of neutrons, leading to variations in atomic mass.

  • The mass number of an atom is the sum of its protons and neutrons.

Average Atomic Mass

  • The average atomic mass of an element is calculated as the average mass of all its isotopes.

  • The weighted average atomic mass considers the abundance of each isotope.

  • average reflects the mass of each atom in a sample and the quantity of each isotope present.

Radioactivity

  • Henri Becquerel discovered that certain elements emit energy spontaneously.

  • Marie Curie named elements that spontaneously emit energy as radioactive, and she termed the emitted energy as radiation.

  • Radiation consists of both energy and particles originating from the nuclei of radioactive elements.

  • When atoms emit radiation, their identity changes, transforming them into different elements.

  • Nuclear decay involves the transformation of an unstable nucleus into a more stable one through the emission of radiation.

Nuclear Decay

  • Nuclear decay can produce various types of radiation.

  • Alpha particles contain two protons and two neutrons.

  • During alpha decay, the atomic number of the decaying atom decreases by 2.

  • Beta decay occurs when a neutron converts into a proton, emitting a high-energy electron known as a beta particle.

  • In beta decay, the atomic number of the atom increases by 1.

  • Gamma rays are high-energy emissions without mass.

  • Gamma radiation does not cause transformation of one element into another.

Radioactive Decay Energy

  • The energy released during radioactive decay can have both beneficial and harmful effects.

Ions

  • Ions are atoms that have become charged due to the gain or loss of electrons.

  • Positive ions result from the loss of electrons.

  • Negative ions result from the gain of electrons.

Question

  • An oxygen ion with a 2- charge indicates that the oxygen atom gained two electrons.