Chemistry: Crash Course

Following videos of Crash Course: Chemistry (https://www.youtube.com/watch?v=QiiyvzZBKT8&list=PL8dPuuaLjXtPHzzYuWy6fYEaX9mQQ8oGr&index=3 to continue creating the flashcards).

6 flashcards · Physics · by lakesare

1. What is Brownian motion?

   Brownian motion is the random motion of particles suspended in a fluid (a liquid or a gas) resulting from their collision with the fast-moving molecules in the fluid. This motion is named after the botanist Robert Brown, who was the most eminent microscopist of his time. In 1827, while looking through a microscope at pollen of the plant Clarkia pulchella immersed in water.

2. What determines which element (e.g. hydrogen) an atom is?

   The number of protons. Proton number only changes when the nucleus undergoes alpha decay, where it essentially becomes a different element.

3. What happens when in the element: amount of protons changes amount of electrons changes amount of neutrons changes

   protons - another element is created (only changes when the nucleus undergoes alpha decay, where it essentially becomes a different element). electrons - element becomes an ion (changes during bonding). neutrons - element becomes a different isotope (like in the emission of beta radiation).

4. What is atomic number? (3 for lithium)

   The atomic number or proton number (symbol Z) of a chemical element is the number of protons found in the nucleus of an atom. It is identical to the charge number of the nucleus. The atomic number uniquely identifies a chemical element.

5. What's a half-life of something?

   Half-life (symbol t1⁄2) is the time required for a quantity to reduce to half its initial value.

6. What do 47 and 107.868 represent?

   47 - atomic number (number of protons) 107.868 - average atomic mass (weighted average of masses of all average isotopes of an element by their abundance)