Chemistry Test 4 Flashcards
Smallest particle of an element capable of chemical interactions
atom
Chemical compounds are composed of a fixed ratio of elements as determined by mass; there are always 2 hydrogens for 1 oxygen in a water molecule
law of definite proportions
streams of electrons that are produced when a high voltage is applied to electrodes in an evacuated tube; used by J.J. Thomson to find that every atom has small, negatively charged particles
cathode rays
A subatomic particle that has a negative charge; found outside the nucleus; has the least mass
electron
the center of an atom, which contains the protons and neutrons
nucleus
A subatomic particle that has a positive charge and that is found in the nucleus of an atom; aka atomic number; discovered by Ernest Rutherford
proton
the number of protons in the nucleus of an atom
atomic number (z)
A subatomic particle that has no charge and that is found in the nucleus of an atom; discovered by James Chadwick
neutron
the major energy levels of an atom (1-7); shells; first quantum number
principal energy level (n)
The lowest energy state of an atom
ground state
a packet of electromagnetic energy
photon
matter (including electrons) can be thought of as having properties of both a particle and a wave
Louis de Broglie
it is impossible to know exactly both the velocity and the position of a particle at the same time
Heisenberg uncertainty principle
a diagramic representation that uses dashes and arrows to show the principal energy levels and sublevels for all the electrons in an atom
orbital notation
Describes the subshell in which an electron is found; s, p, d, f
azimuthal quantum number (l)
the orientation of an orbital around the nucleus
magnetic quantum number (m)
The number that describes the two possible “spin” states of a pair of electrons in an orbital.
electron spin quantum number
two electrons in the same orbital must have opposite spins
Pauli exclusion principle
states that electrons must fill the lowest available energy sublevel before any can be placed in higher energy levels
Aufbau principle
the arrangement of electrons in an atom
electron configuration
electrons occupy orbitals of the same energy in a way that makes the number of electrons with the same spin direction as large as possible; describes how electrons fill orbitals
Hund’s rule
Atoms of the same element that have the same number of protons, but different numbers of neutrons
isotope
the sum of the number of neutrons and protons in the nucleus
mass number (A)
The representation of a specific isotope. The atomic number is listed below the symbol, the mass number above.
isotope notation
alternative unit equivalent to the atomic mass unit
unified atomic mass unit (u)
Electrons on the outermost energy level of an atom
valence electron
an electron-configuration notation in which only the valence electrons of an atom of a particular element are shown, indicated by dots placed around the element’s symbol
electron dot notation
A positively charged ion
cation
A negatively charged ion
anion
sublevel s can hold
2 electrons
sublevel p can hold
6 electrons
sublevel d can hold
10 electrons
sublevel f can hold
14 electrons
The modern periodic table is a model representing
principal energy levels and energy sublevels
T/F The general region of space where an electron is most probably found is known as an orbital.
True
T/F Neutrons contribute to an atom’s mass and its shape
False
T/F An atom that gains three electrons will have a +3 charge
False
T/F Electron dot notation is a shorthand way of showing valence electrons.
True
T/F Each atom can be identified by the number of protons in its nucleus
True
T/F No orbital can hold more than two electrons.
True
T/F An electron can behave only as a wave.
False
T/F The first quantum number identifies the principal energy level of an atom.
True
T/F Scientific models are working representations of experimental facts that have been proven to be correct in all cases.
False
determined by the weighted averages of isotopes of an element
Atomic mass
Energy shells are also called
Energy levels
The highest number of energy levels that atoms can have at ground state
7
Philosophical atomism is a natural philosophy that proposes the universe is made up of indivisible particles called atoms. (Who discovered this?)
Democritus
first experimental atomic model
John Dalton
used the cathode ray tube to discover electrons; plum pudding model
J.J. Thomson
discovered x-rays
Wilhelm Roentgen
Discovered the neutron
James Chadwick
conducted the gold foil experiment and discovered the alpha particle
Hans Geiger
said that electrons are in energy levels; developed the planetary model
Niels Bohr
