Chemical Interactions

Question 1

What is Alchemy?

Answer 1

Alchemy is the investigation of nature and a combination of chemistry and metalwork

Question 2

What were the goals of alchemy?

Answer 2

The goals of alchemy were:
1. To find the “Elixir of Life” (Magical elixir that would bring wealth, health, and immortality)

2. To find the Philosopher’s Stone. When heated and combined with non-precious or base metals it would turn into gold
3. To discover the relationship of humans to the cosmos and use that understanding to improve the human spirit

Question 3

What is central science?

Answer 3

Alchemy itself didn’t survive the Enlightenment. Yet, chemistry continues its quest. Chemistry is called the central science as it connects natural sciences like physics, biology, and geology.

Question 4

What were some important contributions of alchemists worldwide?

Answer 4

1. Indian Alchemist - He described the process of zinc (Zn) production by distillation
2. German Alchemist - Isolated phosphorus (p)
3. German alchemist - developed porcelain (clay material)

Question 5

What are the roots of alchemy/its origins?

Answer 5

In the East in India and China, alchemy started before the common era (CE) with medicine, and meditation to achieve immortality. In the west, alchemy evolved from Egyptian metallurgy.

Question 6

Who was Aristotle?

Answer 6

He proposed that all matter was composed four elements, Earth, Air, Fire and water.

Question 7

Who was Alexander the Great?

Answer 7

He discovered the Greek god Hermes’s famous Emerald Tablet, which was said to have the secret of the philosopher’s stone. He is said to have built the Library of Alexandria specifically to house alchemical texts. These texts were later destroyed.

Question 8

Who were the people after the middle ages?

Answer 8

1. Paracelsus
2. Robert Boyle

Question 9

What did Paracelsus do?

Answer 9

He was the first toxicologist, a person who studies poisons. He proposed that a balance of 3 substances (Mercury, sulfur and salt) was necessary for maintaining health. He believed that the “Alkahest” the supposed universal solvent, was the philosopher’s stone.

Question 10

Who was Robert Boyle?

Answer 10

He created Boyle’s law which stated that the volume of a gas decreases as the pressure on it increases and vice versa. Meaning that Pressure is indirectly proportional to volume.
He is called the Father of Modern Chemistry
Created the copuscularian hypothesis - All matter consisted of varying arrangements of tiny, identical particles called corpuscles and when we change the arrangement of corpuscules, one metal can be converted to another.

Question 11

Who are two recent Chemist / Alchemists

Answer 11

Antoine Lavoisier and Dmitri Mendeleev

Question 12

What did Antoine Lavoisier do?

Answer 12

He is also called the father of chemistry. Gave the law of conservation of mass. Proved Boyle’s corpuscular theory wrong.

Question 13

What did Dmitri Mendeleev do?

Answer 13

Developed the first periodic table

Question 14

What did JJ Thompson do?

Answer 14

He discovered electrons.
He said that an atom consisted of a positively charged sphere on which negatively charged electrons are embedded. An atom as a whole has 0 charges and is electrically neutral

Question 15

What did Ernest Rutherford do?

Answer 15

He tested JJ Thompson’s model. He launched positively charged helium ions at gold foil. Most of the helium ions passed right through. A few came right back and a few deflected. His conclusion was:
1. Most of the space in an atom is empty
2. Positive charge is concentrated in a small portion
3. Most of the mass in an atom is concentrated in the center.

Question 16

Who discovered the Neutron?

Answer 16

James Chadwick

Question 17

Who discovered the proton?

Answer 17

Ernest Rutherford

Question 18

What is an electron cloud?

Answer 18

The region outside the nucleus where the electrons are present

Question 19

How are atoms of elements different?

Answer 19

The atomic structure and bond of each atom are different. There will also be a different number of protons in the nucleus.

Question 20

What is the atomic number?

Answer 20

It is the number of protons in the nucleus of every atom of that element.

Question 21

What are Isotopes?

Answer 21

Isotopes are atoms of the same element that have different numbers of neutrons.
Example:
Carbon - 12, Carbon - 13, Carbon - 14.

Question 22

What is Atomic mass/Mass number

Answer 22

The atomic mass/mass number is the number of protons plus the number of neutrons.

Question 23

What are the physical properties of elements?

Answer 23

They are properties that are seen through direct observation. They are observed from our senses. When undergoing a physical change/property the element remains the same. Physical changes are usually reversible.

Question 24

What are the chemical properties of elements?

Answer 24

One substance changes to another substance. The atomic composition in the atom changes, changing the substance. They are not easily reversible.

Question 25

What is the Periodic table?

Answer 25

It organizes elements according to how they combine with other elements. There are 118 different elements identified. 90 of these occur naturally, the rest are made in labs. They are organized in ascending order of atomic numbers. Each horizontal row is called a period. Each vertical column is called a group.

Question 26

Group 1 metals

Answer 26

They are Alkali metals. They are the first group in the periodic table. They are soft and silvery in pure form. Combine in the ratio of 2 to 1 with oxygen.

Question 27

Group 2 metals

Answer 27

They are Alkaline metals. They are the second group in the periodic table. They combine in a 1:1 ratio with oxygen. Ex: Mg, Ca, Be.

Question 28

What are the Halogens?

Answer 28

They are second from the right in the periodic table. These are elements that tend to be toxic gases or liquids in their pure form. They are also very reactive and are rarely found in pure form. When combined with alkali metals they form salts like NaCl.

Question 29

What does the modern atomic theory state?

Answer 29

The modern atomic theory states that: 1. All matter is composed of atoms 2. All atoms of the same elements are the same; atoms of different elements are different 3. All atoms combine in whole number ratios to form compounds.

Question 30

What are neutral atoms?

Answer 30

They are atoms that have the same number of protons and electrons so the charges cancel out.

Question 31

What is the role of water in Acids?

Answer 31

If the solution has a higher concentration of H3O+ atoms then pure water is considered an acid. Have H+ ions.

Question 32

What is the role of water in bases?

Answer 32

If the solution has a lower concentration of H3O+ atoms then pure water is considered a base. Have OH- ions.

Question 33

What are endothermic reactions?

Answer 33

A reaction is an endothermic reaction if the amount of energy required to break the bonds is greater than the amount of energy released when new bonds are made. Hence it absorbs energy.

Question 34

What are exothermic reactions?

Answer 34

A reaction is an exothermic reaction if the amount of energy released when the new bonds are made is greater than the energy required to initially break the bonds. Hence it releases energy

Question 35

What is energy?

Answer 35

Energy is defined as the ability to do work. All of these forms of energy are stored within an object that is converted to forms of kinetic energy when a force or change is applied.

Question 36

What is chemical energy?

Answer 36

Chemical energy is a form of potential energy and it is possessed by things such as food, fuels and batteries.

Question 37

What is the law of conservation of energy?

Answer 37

It states that energy cannot be created nor destroyed; it can only be converted or transformed.

Question 38

Molecules in a chemical reaction

Answer 38

The chemical energy is stored in the bonds. All chemical changes involve a transfer of energy.

Question 39

What is the source of all chemical potential energy?

Answer 39

The bonds between atoms are the source of all chemical potential energy. A strong bond has less potential energy as it takes more energy to break. A weak bond has more potential energy as it takes less energy to break.

Question 40

What are ionic bonds?

Answer 40

When atoms donate electrons to other atoms ionic bonds form. The atom that lost electron(s) becomes positively charged and the atom that accepted the electron(s) becomes negatively charged. These ions attract each other and bond together based on the attraction of opposite charges. Ex: Na+ + Cl- = NaCl

Question 40

What are ionic bonds?

Answer 40

When atoms donate electrons to other atoms ionic bonds form. The atom that lost electron(s) becomes positively charged and the atom that accepted the electron(s) becomes negatively charged. These ions attract each other and bond together based on the attraction of opposite charges. Ex: Na+ + Cl- = NaCl

Question 41

What are covalent bonds?

Answer 41

When two atoms share an electron it is called covalent bonding. When two atoms are close enough together, there is an attraction between the protons and electrons from one atom and the oppositely charged electrons and protons from another atom. Ex:H+ + H+ = H2.

Question 42

Why do chemical equations have to be balanced?

Answer 42

They have to be balanced as the law of conservation of mass. In every chemical reaction, the same mass of matter must end up in the products as stated in the reactants. Balanced chemical reactions show that mass is conserved, proved by Antoine Lavoisier.

Question 43

What are the cues that tell us a chemical reaction is occurring?

Answer 43

1. A change of color occurs during the reaction 2. A gas is produced during the reaction 3. A solid product called a precipitate is produced 4. A transfer of energy occurs as a result of the reaction