Chemistry: Chapter 4 and 5 [DONE] Flashcards Preview

School > Chemistry: Chapter 4 and 5 [DONE] > Flashcards

Flashcards in Chemistry: Chapter 4 and 5 [DONE] Deck (48):

What did Democritus reason about atoms?

he said that they were indivisible and indestructible; he turned Dalton's ideas into a scientific theory by using scientific methods


What do scientists use to observe atoms?

Scanning electron microscopes


define atom (2)

- the SMALLEST particle of an element

- it retains its identity in a chemical reaction


define Dalton's Atomic Theory: (4)

1. All elements are composed of atoms
2. atoms of the same element are identical, but atoms from different elements are ALL different
3. atoms of different elements can mix together to form a compound
4. chemical reactions occur when atoms are separated from each other, joined, or rearranged in a different combination. *Atoms of one element can NEVER be changed into another element from a chemical reaction.


What are the three types of subatomic particles?

What are their charges?

What are their masses?

- protons, neutrons, and electrons

- positive, neutral, and negative

- 1, 1, 1/1840


What is the actual structure of a nuclear atom?

- Protons and neutrons are contained inside of the nucleus.

- Electrons reside in orbitals AROUND the nucleus


define electron?

who discovered electrons?

- a negatively charged subatomic particle

- J.J. Thomson


define cathode ray:

what was the final results in the experiment conducted by J.J. Thomson

- a glowing beam that Thomson used in an experiment

- found that a positively charged plate ATTRACTS the cathode ray and a negatively charged plate REPELS the cathode ray.


Define proton:

who discovered protons?

- a positively charged subatomic particle

- Ernest Rutherford


define neutron:

who discovered neutrons?

- a neutrally charged subatomic particle

- James Chadwick


define nucleus:

- the center / core of an atom


What was later discovered about atoms?

- that they actually ARE divisible, which means that they can be divided without losing their properties.


what makes one element different from another?

the number of protons

*every element has a different number


How do isotopes of an element differ?

because isotopes of an element have a different number of neutrons and different mass numbers


How to calculate the atomic mass of an element?

(mass of isotope x natural abundance in decimal form = x ) + (mass of isotope x natural abundance in decimal form = x), etc...

* do that for however many isotopes it gives you and then add the products


define atomic number

the number of protons in the nucleus of an atom of the element


define mass number

total number of protons and neutrons in an atom


What did Niels Bohr propose in his model of the atom?

He proposed that an electron is found only in orbits around the nucleus.


what does the quantum mechanical model determine about the electrons in an atom?

the allowed energies an electron can have and how likely It is to find the electron in various locations?


How to find the number of neutrons in an atom?

# of neutrons = mass # - atomic #

* Mass # = rounded to a whole number


define isotope

atoms of the same element that have the same atomic number, but different atomic masses due to a different number of neutrons


How to find protons?

it's the atomic number of an element


define quantum mechanical model

the behavior of electrons in atoms


how to find electrons

*same as the number of protons


define atomic orbital (2)

a mathematical expression describing the probability of finding an electron at various locations

represented by the denser area surrounding a nucleus (higher probability of finding an electron)


define atomic mass

the weighted average of the masses of the isotopes of an element


define atomic mass unit (amu)

a unit of mass equal to one-twelfth the mass of a carbon-12 atom


What were the ideas concerning the structure of an atom involving Thomson and Rutherford?

Thomson - believed that electrons were evenly distributed throughout the atom filled uniformly with positively charged material.

Rutherford - tested Thomson's model of atomic structure through the gold-foil experiment --> led to his idea that the atom was mostly empty space


define energy level

the specific energies an electron in an atom or other system can have


what causes atomic emission spectra? (2)

- absorbing energy (electrons move to higher energy levels)
- emitting light (loses electrons when they return to lower energy levels)


How does quantum mechanics differ from classical mechanics?

- classical mechanics describe the motions of bodies much larger than atoms

- quantum mechanics describes the motions of subatomic particles and atoms as waves


define quantum

the amount of energy needed to move an electron from one energy level to another


define wavelength

what is the unit for wavelength?

- the distance between adjacent crests of a wave

- measured in meters


define frequency

what is the unit of frequency?

- the # of wave cycles that pass a given point per unit of time

- Hertz (Hz) or s^-1


define electromagnetic radiation

energy waves that travel in a vacuum at a speed of 2.998 x 10^8 m/s
(c= wavelength x frequency)


what are the 3 rules for writing the electron configuration of elements?

* what does it do?

1. the Aufbau Principal
2. the Pauli Exclusion Principle
3. Hund's Rule

* it tells you how to find the electron configurations of atoms


how did Einstein explain the photoelectric effect?

he proposed that light could be described as quanta of energy that behave as if they were particles


define atomic emission spectrum

the pattern formed when light passes through a prism


define Planck's Constant

(h) a number used to calculate the radiant energy (E) absorbed or emitted by a body based on the frequency of radiation

E = (6.626 x 10^-34) x frequency


define electron configuration

the arrangement of electrons of an atom in its ground state into various orbitals around the nuclei of atoms


define spin

a quantum mechanical property of electrons that may be thought of as clockwise or counterclockwise


define amplitude

the height of a wave's crest


what is the order of the electromagnetic spectrum from lowest frequency to the highest frequency:

what are the colors?

Radio Waves, Radar, Microwaves, Infrared, Ultraviolet, X-Rays, Gamma Rays

- R.O.Y.G.B.I.V.


order of the electromagnetic spectrum from lowest wavelength to the longest wavelength:

Gamma Rays, X-Rays, Ultraviolet, Infrared, Microwaves, Radar, Radio Waves


define photoelectric effect:

the ejection of electrons by certain metals when they absorb light with a frequency above a threshold frequency


define photon

a quantum (amount of energy needed to move an electron from one level to another) of light

- a discrete bundle of electromagnetic energy that interacts with matter similarly to particles


define ground state

the lowest possible energy of an atom described by quantum mechanics


define Heisenberg uncertainty principle

it is impossible to know exactly both the velocity and the position of a particle at the same time