Dalton's Atomic Theory, Rutherford's Model and Chemical Bonding Basics
Dalton's Atomic Theory
What are the postulates of Dalton's atomic theory?
- Matter consists of discrete particles called atoms, which are tiny and indivisible and cannot be destroyed in any chemical process.
- Atoms of the same element are identical in mass, size and other physical and chemical properties.
- In chemical reactions, atoms are neither created nor destroyed; they only change their distribution.
- Compounds are formed when atoms of different elements combine in fixed, whole-number ratios to form molecules of the same composition every time.
Rutherford's Atomic Model
Who proposed the first atomic model based on the planetary system?
Rutherford proposed that the atom has a small, dense, positively charged central nucleus that contains almost the entire mass of the atom. Electrons revolve around the nucleus in circular orbits at relatively large distances. The sum of the negative charges of the electrons equals the positive charge of the nucleus, so the atom is electrically neutral.
Thomson's Model
How did Thomson's model differ from Rutherford's regarding the atom? Thomson's model stated that the atom contains equal amounts of negative and positive charges.
Rutherford's Gold Foil Experiment
What conclusion did Rutherford reach from the first bombardment of a gold foil with radiation? Most emissions passed through the foil, some were deflected, and a few were reflected back, showing that the atom is mostly empty space with a small, dense, positively charged nucleus.
Atomic Orbitals and Wave Functions
What is an atomic orbital? An atomic orbital is the region where an electron is most likely to be found. Wave functions describe the stationary states of single-electron atoms, such as hydrogen-like atoms.
Isotopes, Covalent Bonds and Chemical Bonding
Define isotope, covalent bond and chemical bond.
Isotopes are atoms of the same element that have the same number of protons but a different number of neutrons. A covalent bond consists of the sharing of electron pairs between two atoms, giving rise to polar or nonpolar molecules. A chemical bond is the physical process responsible for the attractive interactions between atoms and molecules.
Ionic Bonds
What type of bond forms when the difference in electronegativity between two elements is greater than 2? An ionic bond.
Electron Configuration and Noble Gases
Write the electron configuration of fluorine: 1s2 2s2 2p5.
What are the characteristics of noble gases that give them stability? Noble gases have completely filled energy levels and sublevels, which makes them chemically stable and unreactive.
Ions, Cations and Anions
Define ion, cation and anion.
An ion is an atom or molecule with an electric charge. Cations are positive ions, while anions are negative ions.
Atomic Number, Mass Number and Valence Electrons
Define atomic number (Z) and mass number (A).
The mass number (A) is the total number of protons and neutrons in the nucleus of an atom. The atomic number (Z) is the number of protons in the nucleus, which is equal to the total number of protons in the atom.
Valence electrons are the electrons in the outermost energy level of an atom.
An electron configuration describes the location of electrons in the orbitals of the different energy levels.