Chapter 1: Atomic Structure Flashcards
(15 cards)
What is the structure of an atom in terms of electrons, protons, and neutrons?
Atoms consist of a central nucleus containing protons (positive) and neutrons (neutral), with electrons (negative) moving in energy levels (shells) around the nucleus.
Where is most of the mass and charge located within an atom?
Almost all the mass is in the nucleus (protons and neutrons). The nucleus is positively charged. Electrons have negligible mass and are negatively charged, occupying most of the atom’s volume.
How do you deduce the numbers of protons, neutrons, and electrons in atoms and ions?
Proton number = number of protons = number of electrons (in a neutral atom). Nucleon number = protons + neutrons. For ions: adjust electron count depending on the charge.
What is the relative mass and charge of protons and neutrons?
Proton: relative mass = 1, charge = +1. Neutron: relative mass = 1, charge = 0.
What are isotopes?
Isotopes are atoms of the same element (same number of protons) with different numbers of neutrons.
How do protons, neutrons, and electrons behave in an electric field?
Protons deflect toward the negative plate. Electrons deflect toward the positive plate. Neutrons do not deflect.
What is the contribution of electrons to atomic structure and charge?
Electrons determine the atom’s overall charge and chemical properties due to their arrangement in shells.
What happens when electrons in atoms move between energy levels?
Electrons absorb energy to jump to higher levels (excitation) or emit energy as light when they fall to lower levels (emission).
Why are electron energy levels important in emission and absorption spectra?
Each element has unique energy levels. Electrons transitioning between levels absorb or emit specific wavelengths, producing characteristic spectra.
Define ground state and excited state of electrons.
Ground state: the lowest energy level an electron occupies. Excited state: a higher energy level an electron can temporarily occupy after gaining energy.
What are line spectra from excited atoms indicative of?
Line spectra are due to electrons moving from higher to lower energy levels, releasing specific photon energies.
What is first ionisation energy?
The energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous positive ions.
What are the trends in first ionisation energies across a period?
Across a period: increases due to increasing nuclear charge and decreasing atomic radius.
What are the trends in first ionisation energies down a group?
Down a group: decreases due to increased distance from nucleus and more shielding.
How do ionisation energies provide evidence for electron sub-shells and energy levels?
Sharp increases in successive ionisation energies suggest new energy levels or sub-shells.
