Unit 1 Study Flashcards
(47 cards)
What are the four classical elements in early atomic theory?
Earth, fire, air, and water
These elements were believed to be in Brownian motion within a void.
What did Dalton’s Atomic Theory state about atoms?
Atoms are the tiniest substance, element’s atoms are identical, atoms vary by element, compounds consist of two or more elements, and conservation of mass
Dalton’s theory laid the foundation for modern chemistry.
Who discovered electrons and how?
JJ Thomson using a cathode ray tube
He demonstrated that electrons are negatively charged particles smaller than hydrogen atoms.
What is the Plum Pudding model?
Model where the atom is a blob with electrons scattered throughout
Proposed by Thomson after his discovery of electrons.
What did Rutherford discover about the atom?
That there is a dense area within the atom, known as the nucleus
This was discovered through the deflection of alpha particles in foil bombardment experiments.
What is the Planetary Model of the atom?
Electrons move around the nucleus like planets around the sun
This model was created despite known issues with circular orbits.
What is the mass of a single atom defined as?
1 AMU(weight of 1 carbon-12)
Defined using the mass of one atom of carbon-12 (12 amu).
What is the difference between mass number and atomic number?
Mass Number (A) = protons + neutrons; Atomic Number = number of protons
The atomic number also indicates the number of electrons in a neutral atom.
What are isotopes?
Atoms with the same number of protons and electrons but different numbers of neutrons
Only the weight changes among isotopes.
What does Coulomb’s Law state?
Opposite charges attract and like charges repel, include gravitational, electrostatic, weak nuclear, strong nuclear
This law describes the electrostatic force between charged particles.
What is the gravitational force?
A force between objects that have mass, always attractive
It is described by Newton’s Law of Universal Gravitation.
What is kinetic energy (KE)?
Energy observed in motion, calculated as KE = ½(m)(v^2)
Kinetic energy increases with the speed of the object.
What is potential energy (PE)?
Energy associated with the position of a system
It changes with the position of objects within a field.
What are London Dispersion Forces?
Attractive forces that exist within all neutral solid and liquid atomic structures due to electrons clouds focusing electrons in one area and creating electrostatic forces.
They arise from temporary dipoles created by electron movement.
How do London Dispersion Forces increase?
With the number of electrons and surface area
More electrons lead to a higher likelihood of distortion and induced dipoles.
What is the significance of a deeper potential energy well?
Indicates a higher boiling point due to the required energy to break bonds
For example, argon has a higher boiling point than neon due to more electrons.
What is a covalent bond?
A bond formed when non-noble gases share electrons
Covalent bonds lead to the formation of new compounds, such as H2.
What is stoichiometry?
The relationship between the macroscopic and molecular level
It involves balanced equations to describe chemical reactions.
What is the mole unit?
A unit for the number of atoms in 12g of C-12, equal to 6.022x10^23
It is used as a universal conversion unit.
What is a solution in chemistry?
A homogeneous mixture of two or more components
The solute is the minor quantity that dissolves in a solvent, the major component.
How are gravitational and electrostatic forces measured
G: M1M2/r^2 E:Q1Q2/R2 r=distance
Dalton’s Atomic Theory
Atoms are tiniest subtance on earth with each element having identical atoms
What was JJ thomsons experiment
He found the existence of electrons through a cathode ray tube and proved something was lighter than H
What was JJ Thomson’s model
Plum Pudding Model-atoms are blobs with electrons scattered throughout it randomly
