Things Flashcards
Who proposed the Plum Pudding model of the atom?
J.J. Thomson in 1897.
What does the Plum Pudding model suggest about the structure of an atom?
The atom is a ball of positive charge with electrons embedded in it like ‘plums’ in a ‘pudding.’
What evidence led to the rejection of the Plum Pudding model?
The alpha scattering experiment (Rutherford’s experiment) showed that the atom has a small, dense, positively charged nucleus.
Who conducted the Alpha Scattering Experiment?
Ernest Rutherford in 1909.
What was the aim of the Alpha Scattering Experiment?
To investigate the structure of the atom by firing alpha particles at a thin gold foil.
What were the main findings of the Alpha Scattering Experiment?
Most alpha particles passed through the foil, some were deflected at small angles, and a few were reflected, indicating the presence of a dense nucleus.
What model replaced the Plum Pudding model based on this experiment?
Rutherford’s Nuclear Model of the atom.
What type of particle is emitted in alpha radiation?
An alpha particle, which consists of 2 protons and 2 neutrons.
What is the charge of an alpha particle?
+2 (positive charge).
What type of radiation is beta radiation?
Beta particles, which are high-energy electrons (β⁻).
What is the charge of a beta particle?
-1 (negative charge).
What type of radiation is gamma radiation?
Gamma rays, which are high-energy electromagnetic radiation (photons).
How does alpha, beta, and gamma radiation affect atomic number and mass number?
Alpha: Decreases atomic number by 2, mass number by 4. Beta: Increases atomic number by 1, mass number stays the same. Gamma: No change in atomic or mass number.
How does the reactivity of alkali metals change as you move down the group?
Reactivity increases down the group.
Why does reactivity increase in alkali metals as you go down the group?
The outer electron is further from the nucleus and more easily lost due to increased shielding.
