2.1-2.3 Chapters: Matter &

Question 1

Stone Age?

Answer 1

• First chemists lived before 8000 BC in Middle East.
• Stone Age was characterized by use of stone tools.
• Fire control and substance change skills developed.
• Fire-hardened mud bricks and stronger tools made.
• Metals discovered by end of Stone Age, leading to bronze age.

Question 2

Bronze Age?

Answer 2

• Chemists focused on metals like gold and copper.
• Gold’s attractive color and lustre made it valuable.
• Copper’s use in tools, pots, coins, and coins made it valuable.
• Copper experimentation led to creation of bronze.
• Hittites discovered iron extraction around 1200 BC, triggering the Iron Age.

Question 3

Iron Age?

Answer 3

• Iron and carbon combined to create steel.
• Steel enhanced hunting blades and war armour.
• Early people explored liquid extraction and use.
• Juices and oils crucial in daily life and rituals.
• Ancient Egypt preserved human bodies with Juniper tree resins.

Question 4

Composition Of Matter - Democritus

Answer 4

• Greek philosophers proposed matter as composed of particles around 2500 years ago.
• Democritus used “atomos” in 400 BC to describe smallest particles.
• Each material type was composed of different atomos with unique properties.
• Aristotle’s 350 BC claim of earth, air, fire, and water was widely accepted.

Question 5

Alchemy

Answer 5

Ancient branch of natural philosophy.
* Originated in Greece and Egypt.
* Experimented with transforming metals into valuable ones.
* Transformed ordinary into extraordinary.

Question 6

Alchemist

Answer 6

An ancient scientist who was thought to be part chemist ­ part magician.

Question 7

What Did Alchemists Do?

Answer 7

Conducted various chemistry experiments.
* Invented lab tools like beakers and filters.
* Published Alchemia, the first printed chemistry text in 1597.

For Example: Al-Razi discovered plaster of paris which is a material used to heal broken bones.

Question 8

Robert Boyle?

Answer 8

Confirmed matter composed of tiny particles.
* Observed gas behavior.
* Believed particles group together to form substances.

Question 9

Antoine Laurent Lavoisier

Answer 9

1770s study of chemical interactions.
* Developed naming system for chemicals.
* Identified hydrogen, oxygen, and carbon.
* Known as “Father of Modern Chemistry.”

Question 10

J.J. Thompson

Answer 10

Discovered subatomic particle, electrons.
* Experimented with cathode rays, identifying negatively charged particles.
* Proposed “Raisin Bun Model” of atom in 1897.
* Described positively charged sphere with negative charges.
* Believed in balanced positive and negative charges.
* Cathode rays used in TVs for image creation.

Question 10

John Dalton

Answer 10

Developed theory based on experiments.
* First to define an element as a pure substance.
* Each element is composed of an atom.
* All atoms of the same element have identical masses.
* No two elements have the same mass.
* Known as the “billiard ball model” due to atoms’ solid spheres.

Question 11

Hantaro Nagaoka

Answer 11

Created miniature solar system.
* Positive charges at center, negative charges orbit.

Question 12

Ernest Rutherford

Answer 12

Utilized radioactivity to create atom model.
* Predicted particles would travel straight through foil, some scattered.
* Atoms mainly empty space, with a tiny, positively charged center at the core, referred to as the nucleus.

Question 13

Niels Bohr

Answer 13

Believed electrons orbit in specific circular shells.
* Electrons jump between shells due to energy gain or loss.

Question 14

James Chadwick

Answer 14

Chadwick’s Nucleus Discovery
* Nucleus contains protons and neutrons.
* Both have equal mass.

Question 15

Quantum Mechanics

Answer 15

Quantum Mechanics ­ A branch of physics that describes properties of nature on an atomicscale.Quantum Mechanics Modifies Chadwick’s Atom Model
* Electrons in charged cloud around nucleus.

Question 16

Origins Of The Periodic Table

Answer 16

Over 30 elements identified by early 1800s.
* John Dalton developed new symbols for elements, improving communication.
* Berzelius modified Dalton’s work, suggesting letters for each element.
* First upper case letter of an element became the symbol.
* For elements with same first letter, a second lower case letter was added.
* Berzelius’s naming system is still used today, facilitating understanding among chemists.

Question 17

The Atomic Mass?

Answer 17

­ The mass of one atom of an element ­ measured in atomic mass units ( amu).Chemists decided to order the elements by increasing atomic mass. They determined the average mass of an atom by comparing it to the mass of a carbon atom.

Question 18

Octave

Answer 18

In 1864, John Newlands recognized a pattern when elements were listed by increasingatomic mass. The properties of elementsrepeated at regular intervals. Newlands called this pattern the “Law of Octaves”.

Question 19

Electrolysis

Answer 19

The process of decomposing a chemical compound by passing an electric current through it.Scientists used electrolysis to isolate the elements potassium, sodium, magnesium, calcium, strontium, and Barium

Question 20

Covalent Bond

Question 21

Dimitri Medeleev

Answer 21

Organized elements based on patterns in their properties.
* Examined 63 known elements and their properties.
* Developed pattern for predicting properties of undiscovered elements.
* His work accurately reflected nature.

Question 22

Periodic Table Now

Answer 22

Mendeleev’speriodic table included the 63 elements of his time. Since then, many more elements have been discovered. Today, about 118 elements are known.

Question 23

Atomic Number?

Answer 23

Represents the number of positively charged protons in an element’s nucleus.
* Located above the element’s symbol on the left.
* Oxygen atoms have 8 electrons due to their neutrality.
* The atomic number increases by 1 for each element in the periodic table.

Question 23

Element Symbol and Names

Answer 23

Most elements are abbreviations from their modern or Latin chemical names.
* Examples include Si for Silicon, Mn for Manganese, and Au for Gold.
* Some elements are named after their discovery locations.
* Examples include Californium (Cf) discovered in 1950 in California and Polonium (Po) discovered in Poland.
* Some elements are named after scientists who made significant contributions to their field.

Question 24

Atomic Mass?

Answer 24

Atomic Mass: Total mass of protons and neutrons in an atom.
* Electrons have minimal effect on total mass.
* Atomic Number: Sum of all protons and neutrons.
* Often equals to Number of Neutrons.
* Example: 16 - 8 = 8 neutrons.

Question 25

Ion Charge?

Answer 25

Ions are atoms with an electric charge, not neutral.
* Ion charge is created by the gain or loss of electrons.
* Oxygen atom has an ion charge of -2, indicating 2 electron gain.

Question 26

Groups and Periods Of Periodic Table

Answer 26

Groups are numbered 1 to 18 with similar properties.
* Named by the first element in the column.
* Hydrogen is an exception, often placed separately from other elements.
* Periods are numbered 1 to 7, with properties changing from metals to non-metals.
* Most reactive metals start on the left, becoming less reactive as you move to the right.

Question 27

Metals

Answer 27

Metals ­ These elements are shiny , malleable , and ductile . They conduct electricityand are good thermal conductors.

Question 28

Non-Metals

Answer 28

Non­Metals ­ These elements can be a solid or a gas . The solid ones are dull and brittle. Non­Metals do not conduct electricity, and are good insulators.

Question 29

Noble Gases

Answer 29

Previously believed in inability to combine with other elements.
* Neil Bartlett made the first noble gas compound in 1962.

Question 30

Metalloids

Answer 30

Metalloids ­ These elements have both metallic and non­metallic properties.