30 Questions
Which model is known for its simplicity and visualization of energy levels?
Bohr model
Which branch of physics deals with matter and energy at atomic and subatomic levels?
Quantum Mechanics
What are the three subatomic particles within an atom?
Protons, Electrons, Neutrons
What charge does a Cation have?
Positive
Which property uniquely identifies each element and is equal to the number of protons in its nucleus?
Atomic Number
What is the formula to calculate the number of neutrons in an atom?
$\text{Mass Number} - \text{Atomic Number}$
What do Anions represent?
A negative charge
Which particle interacts with other atoms to form chemical bonds?
Electrons
What is the symbol for an atom with an excess of 4 electrons?
Si4-
What is the main difference between the Bohr model and the quantum-mechanical model in predicting electron location?
Shape of orbitals
Who first used the word 'atomos' to describe indivisible particles of matter?
Democritus
According to Dalton's atomic theory, atoms of the same element are:
Alike in all aspects
In the Plum Pudding Model, the atom is described as:
A positively charged material with electrons embedded within
The Saturnian Model of the atom was proposed by:
Hantaro Nagaoka
What experiment provided evidence for the existence of a compact nucleus in the atom?
Alpha particle scattering experiment
According to the Nuclear Model of the atom, which of the following statements is true?
Electrons orbit the nucleus in distinct, spherical orbits
Which experiment demonstrated the energy levels of electrons in atoms?
Flame test experiment
Which model of the atom described electrons orbiting the nucleus like the rings of Saturn?
Saturnian Model
Who discovered the electron, which inspired the development of the Plum Pudding Model?
J.J. Thomson
Which scientist's work established that electrons move in distinct, spherical orbits with specific energy levels?
Niels Bohr
What is the average mass of carbon if it were 100% carbon-13?
13 u
If carbon were a 50/50 mix of carbon-12 and carbon-13, what would be its average mass?
12.5 u
What is the actual percentage of carbon-12 in naturally occurring carbon?
98.93%
What is the weighted average atomic mass of lithium, given its abundances are 92.4% lithium-7 and 7.6% lithium-6?
6.924 u
Which isotope of bromine is more common?
Bromine-79
What is the weighted average atomic mass of chlorine, given its abundances are 75.8% chlorine-35 and 24.2% chlorine-37?
35.484 u
If carbon had a 75% abundance of carbon-12 and a 25% abundance of carbon-13, what would be its average mass?
12.25 u
What is the atomic mass of carbon listed on the periodic table?
12.01 u
If bromine had an atomic mass of 80 u, which isotope of bromine would be more abundant?
Bromine-81
What is the mass of the chlorine-35 isotope?
35 u
Study Notes
Atomic Structure
- The atom is composed of three subatomic particles: electrons, protons, and neutrons.
- Electrons are found outside the nucleus, while protons and neutrons are found in the nucleus.
- Electrons interact with other atoms, and their properties are:
- Symbol: e-
- Charge: -1e
- Mass: 9.194 x 10^(-31) kg, or approximately 1/1836 u
- Protons have a:
- Symbol: p+
- Charge: +1e
- Mass: 1.6726 x 10^(-27) kg, or approximately 1 u
- Neutrons have:
- Symbol: n
- Charge: 0
- Mass: 1.6749 x 10^(-27) kg, or approximately 1 u
Properties of Atoms
- Atomic Number: the number of protons in an atom, which is unique to each element and determines the element's identity.
- Mass Number: the sum of protons and neutrons in an atom, which is unique to each isotope.
- Isotopes: atoms of the same element with the same atomic number but different mass numbers.
- Ion Notation: 𝐴 𝑋 𝑍, where A is the mass number, X is the chemical symbol, and Z is the atomic number.
Ions
- Ions are atoms with an excess or lack of electrons.
- Anions have an excess of electrons and a negative charge.
- Cations have a lack of electrons and a positive charge.
- Ion symbols: Cu²⁺, Mg³⁻, K⁺, etc.
Atomic Mass
- Atomic mass is the weighted average of the masses of all the stable isotopes of an element in nature.
- It is usually a decimal value.
- Units are atomic mass units (u), defined as 1/12th of a carbon-12 atom.
Model Development of the Atom
- Democritus proposed the concept of indivisible particles (atoms) in 400 BCE.
- John Dalton developed a comprehensive theory of atoms in the early 1800s.
- J.J. Thomson discovered the electron in 1897 and proposed the Plum Pudding Model.
- Hantaro Nagaoka proposed the Saturnian Model in 1904.
- Ernest Rutherford confirmed the existence of a nucleus with alpha particles.
- Niels Bohr established that electrons move in distinct, spherical orbits with specific energy levels.
Explore the historical development of the atom model from Democritus and John Dalton to J.J. Thomson. Learn about key contributions and theories that laid the foundation for modern atomic theory.
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