Chemistry theorists

Question 1

1

What is Alchemy?

Answer 1

• Ancient Branch of Natrual Philosophy which came before modern chemistry. Originated in ancient Egypt and Greece.
• Blended mysticism with experimental practices to change matter transforming base metals into silver or gold, and to discover the philosphers stone.
• Islamic scholar Jabir Ibn Hayyan advanced alchemical techniques including distillation and acid production.
• (3500 BC)

Question 2

2

What is Alchemy?

Answer 2

• European alchemists like Paracelsus shifted the focus twoards medical applications. The mystical aspects like transmutation were debunked by the 17th century.
• Alchemys experimental methods laid the groundwork for modern chemistry.
• Scientists like Robert Boyle & Antoine Lavoisier ultimately replaced alchemy with emperical, scientific approaches leading to major discoveries like the conservation of mass and modern chemical nomenclature.

Question 3

Democritus

Answer 3

• Ancient greek philosophers.
• Proposed that all matter is made up of small indivisble particles called atoms (atomos). He believed these atoms were eternal, indestructible & varied in shape and size, moving through the empty space to form the different substances in the world. Democritus’s ideas were philosophical, not experimental, but they laid the foundation for later atomic theory in chemistry.
• (430 bce)

Question 4

ANCIENT GREEK PHILOSPHER

Aristotle

Answer 4

• Rejected Democritus’s atomic theory.
• He proposed that matter was made up of four fundamental elements: earth, water, air and fire.
• He believed that all substances were composed of these elements in different proportions, and that substances could transform by changing these proportions.
• Aristotle also introduced the concept of “Qualities” like hot, cold, wet & dry, which he believed defined the properties of materials.
• (450 bce)

Question 5

1

John Dalton

Answer 5

• Made significant contribuitions to the development of modern atomic theory
• proposed that all matter is made up of indivisble atoms, each of which is a fundamental, unchangeable unit. This was a pivotal shift from earlier ideas that matter was continuous.
• When elements combine, they do it in ratios of small whole numbers. This has helped support the idea of atoms combining in fixed ratios to form compounds.
• (1803)

Question 6

2

John Dalton

Answer 6

• His work led to the groundwork for understanding chemical reactions as interactions between atoms. Atoms of different elements have different weights and combine in fixed ratios to form compounds.
• He made a system assigning relative weights to atoms, which was an early of what is now known as atomic mass.

Question 7

J.J Thomson

Answer 7

• Discovered the electron by use of cathode rays which he determined were streams of negatively charged particles.
• He created the “plum model” in which matter contained evenly distributed positive charges.
• He called the negatively charged particles “corpuscles” aka electrons.
• (April 30th, 1897)

Question 8

Ernest Rutherford

Answer 8

• Conducted a study on alpha particles being aimed at thin gold sheets. The alpha particles were positively charged.
• Most of them passed through without changing course at all, some bounced of like they hit something solid.
• He knew that positive charges repel positive charges
• He concluded that an atom had a small,dense, positively charged center that repelled has positively charged “bullets”.
• All of an atoms positively charged particles were contained in the nucleus & the negatively charged particles were scattered outside the nucleus around the atoms edge.
• (1911)

Question 9

Niels Bohr

Answer 9

• Placed each electron in a specific energy level.
• According to Bohr’s atomic model, electrons move in definite orbits around the nucleus, much like how planets orbit the sun.
• -> these orbits, or energy levels, are located at certain distances from the nucleus.
• (1913)

Question 10

Schrodingr

Answer 10

• Combined Equation of the behaviour of waves with the De Broglie equation to generate a model for the atom that accurately calculated energy levels of electrons.
• His model and equation suggested that electrons behave as both particles and waves.
• His discoveries are very important to quantam mechanics.
• He basically just discovered a wave equation that accurately calculated the amount of energy levels of electrons in atoms
• (1926)