Sandra found these notes in her notebook: 1. in 1897, j. j. thomas discovered electrons. 2. in 1913, niels bohr found evidence that electrons are arranged in energy levels. 3. in 1926, erwin schrödinger’s work led to the electron cloud model. her notes refer to a. some of the discoveries that led to the development of the atomic law. b. when schrödinger’s electron law became a theory. c. when schrödinger’s electron hypothesis became a law. d. some of the discoveries that led to the development of the atomic theory.

Answer is: D. some of the discoveries that led to the development of the atomic theory.

1) J. J. Thomson discovered the electron in 1897.

His "plum pudding" model (1904) suggested: the electrons are embedded in the positive charge.

With this model, he abandoned his earlier hypothesis (the atom was composed of immaterial vortices).  

2) According to the Bohr model of the atom:

1. Electrons orbit the nucleus in orbits that have a set size and energy.

2. Energy levels of electrons are discrete (certain discrete values of energy).

3. Electrons can jump from one energy level to another, absorbing or emitting electromagnetic radiation with a frequency ν (energy difference of the levels).

3) According to electron cloud model: the most likely location where an orbiting electron will be found is called electron orbitals.

its d ok plz trust me its d

alkaline metals are lithium, sodium, rubidium, potassium, cesium and francium.

alkali metals have electronegativity from 0.7 to 1, lowest in periodic table of elements, which means that alkali metals (i group in periodic table) has positive oxidation number in compounds.

electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

alkaline metals (far left in main group) have lowest ionizations energy and easy remove valence electrons,

for example, potassium is the alkali metal and has a single valence electron in the outer electron shell.

electron configuration of potassium is: ₁₉k 1s²2s²2p⁶3s²3p⁶4s¹.

they can not exist alone in nature, because they are very reactive.