Unit B | Topic 3 | Atoms / Laws, theories, observations Flashcards
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Who was the first person to ever theorize “the atom”?
Democritus:
Described the smallest particles as “atomos”, meaning “indivisible”
Who was Aristotle and what did he contribute to the study of atoms?
- A Greek philosopher who opposed Democritus
- Stated that everything is made of either earth, fire, water, or air.
How long was Aristotle’s theory on the atom taken as fact for?
2000 years
Definition of:
Alchemist
Someone who was part magician and part scientist (around pre 1500’s)
The study of Alchemy is also known as:
Pseudo-science
What did alchemists in the pre 1500’s seek out to perform?
Turn any metal into gold, but they were not interested in truly understanding matter
What did Robert Boyle contribute to the study of matter?
- Realized that elements form compounds
- Believed that the purpose of chemistry was to determine the kinds of particles in any substance
What did Sir Francis Bacon contribute to the study of matter? (And what time frame?)
Proposed that science should be based on experimental evidence instead of thoughts or ideas (1500’s)
What did Antoine Lavoisier contribute to the study of matter?
- Known as the “father of modern chemistry”
- Discovered 23 pure elements
- He was very careful with experiments and kept organization over research and data
- Created the law of conservation of mass
Definition of:
Law of conservation of mass
In a chemical change, the total mass of a new substance is the same as the total mass of the original.
Definition of:
Law of definite composition
Compounds are pure substances that contain two or more elements that are always in fixed proportions
Example of:
Law of definite composition
Water (H2O) will always contain 2 Hydrogen and 1 Oxygen
What was Dalton’s Atomic theory?
- All matter is made up of atoms
- Atoms can’t be created, destroyed, or divided
- All atoms of the same element are the same in mass and size
Definition of:
Law (in science)
An action or condition that has been observed so constantly that scientists are convinced it will always happen
Definition of:
Theory
An explanation of an event that has been supported by consistent results and is accepted by a majority of scientists
Definition of:
Model
A mental image used to help explain an event
Definition of:
Observation
The use of senses to gather informtation
What did J J Thompson discover and contribute to chemistry?
- Created the “plum pudding” model (kinda looks like a cookie though)
- Discovered and named negatively charged particles (electrons)
- Reasoned that there must be positively charged particles (protons)
What did Rutherford discover and contribute to chemistry?
- Most of an atoms mass is in the center (nucleus)
- Named the positively charged particles Protons
- Theorized that neutrally charged particles, called neutrons, exist
What did Bohr discover and contribute to chemistry?
- Pictured an atom as a “solar system”
- Electrons rotate around the nucleus
- Stated that electrons are found in fixed pathways called orbits
What does the “cloud” atomic model theorize?
Electrons have levels but there’s a “cloud” around the nucleus where they’re most likely found
What are all atoms made of?
3 subatomic particles
What are the three subatomic particles?
- Protons
- Neutrons
- Electrons
Where are Protons and neutrons found in an atom?
The nucleus
Where are Electrons found in an atom?
Electron shells (orbits)
What charge do Protons have
A positive charge
(P for positive)
What charge do Electrons have?
A negative charge
What charge do Neutrons have?
None (the are neutral)
(N for neutral)
Together, what do both Protons and neutrons make up?
The atomic nucleus
In a Bohr diagram, what does the top number represent?
The amount of Protons (and electrons) in an atom
True or False:
Neutral atoms have a different number or protons and electrons
False:
Neutral atoms, since they’re neutral, have the same amount of protons and electrons
In a Bohr diagram, what do the large letter(s) represent?
A name of a certain element
How do you determine how many “rings” an atom has?
The row number of that specific atom
How do you determine how many electrons can be contained in a certain ring?
The number that is located under the group (column) the element is located in
How many electrons can each shell hold?
1st shell: 2
2nd shell: 8
3rd shell: 8
4th shell: 18
5th shell: 18
6th shell: 32
7th shell: 32
Definition of:
Valence Electrons
The electrons on the outer most ring of an atom that can react with other atoms
Definition of:
Anions
Negatively charged ions (they have more electrons than protons)
Definition of:
Cations
Positively charged ions (they have less electrons than protons)
Why do atoms attempt to gain or lose electrons?
To have a full shell of valence electrons
