A1.3 - developing ideas about matter

Question 1

What is chemistry?

Answer 1

Understanding the nature of matter, and changing matter in useful ways

Question 2

Who were the first chemists?

Answer 2

Ancient Egyptians may have been the first chemists, eye makeup was recovered preserves in tiny vases in tombs and shown to be made of chemical compounds that do not occur naturally

Question 3

What are five ways humans use chemistry to prepare and preserve food?

Answer 3

Drying, dehydration, freezing, fermentation, chemical preservation

Question 4

What is fermentation?

Answer 4

A biomechanical preservation technique where bacteria called Lactobacilli converts starches and sugars into a chemical called Lactic acid, which prevents the growth of bacteria that cause food to rot

Question 5

What is smoking?

Answer 5

Smoking food introduces chemicals called antioxidants that slow the rotting process

Question 6

What is metallurgy?

Answer 6

A branch of chemistry, the science of producing and using metals

Question 7

What is annealing?

Answer 7

The heating of copper before hammering, making it less brittle so it could be turning into stronger tools and weapons

Question 8

What is smelting?

Answer 8

The process of separating a metal from other elements in the compound (when copper and tin are smelted, they make bronze, and iron is smelted with carbon to create steel)

Question 9

What did Aritotle believe about matter?

Answer 9

Aristotle believed that all matter was composed of fire, earth, water, and air (Fire=dry/hot, earth=dry/wet, water=cold/wet, air=hot/wet)

Question 10

What did Democritus believe?

Answer 10

He believed all matter was made of tiny particles that could not be divided into smaller pieces, called Atomos

Question 11

What is Alchemy?

Answer 11

A combination of magic and science (The goal of alchemy was to get rich turning common metals into precious metals)

Question 12

Who was Robert Boyle?

Answer 12

Concluded that gasses are made up of tiny particles that group together to make different substances

Question 13

Who was Antoine Lavoisier?

Answer 13

Concluded that mass is neither produced nor lost during a chemical reaction
He called this the Law of Conversation of Mass

Question 14

Who was John Dalton?

Answer 14

Imagined atoms as small spheres with different properties (varying in size, color, mass)
- All matter is made up of tiny particles, invisible to the eye
- All the atoms in an element are identical in properties
- Atoms of different elements have different properties
- Atoms of different elements can combine in specific fixed ratios to form new substances

Question 15

Who was J.J. Thomson?

Answer 15

• He discovered the electron by experimenting with beams of particles in a vacuum tube
• He saw the beams were made of a negative charge
• He stated that all atoms were made of smaller subatomic particles put together in different ways to make different elements

Question 16

Who was Ernest Rutherford?

Answer 16

• Discovered the nucleus of an atom by shooting particles at a sheet of gold foil
• A very small amount were deflected, while most of them went through the foil
• He concluded that the atom is mostly empty space, but has a tiny, dense, positively charged core

Question 17

Who was Neils Bohr?

Answer 17

• Proposed that electrons surrounds the nucleus in different energy levels (shells)
• ## He used the colors of particle levels

Question 18

What is the Quantum Mechanical Model of the Atom?

Answer 18

• Each electron is a cloud of negative charge, instead of a tiny, negative particle
• Electrons occupy the whole space at once instead of a tiny negative particle
• Schrödinger’s cat thought experiment