Unit 2 Flashcards
What is the smallest representative particle of an element?
An atom.
What is smaller than an atom?
A subatomic particle: protons, neutrons, and electrons
Define cathode rays.
Streams of electrons that are produced when a high voltage is applied to electrodes in an evacuated tube.
Spontaneous disintegration of an unstable atomic nucleus with accompanying emission of radioactivity is known as what?
Radioactivity
What is the nuclear model of the atom?
The model of the atom with a nucleus containing protons and neutrons and with electrons in the space outside the nucleus.
What’s the nucleus of an atom?
The nucleus is the very small, very dense, positively charged portion of an atom and is composed of protons and neutrons.
What is a positively charged particle in the nucleus of an atom?
A proton.
Neutrons are what?
Neutrons are electrically neutral particles found in the nucleus of an atom. They have approximately the same mass as a proton.
Electrons are subatomic particles with what electrical charge?
Electrons are negatively charged particles surrounding the nucleus of the atom.
What is the negative charge carried by an electron?
Electronic charge
What is an Atomic Mass Unit (amu)?
An amu is based on the value of exactly 12 amu for the mass of the carbon isotope that has 6 protons and 6 neutrons in the nucleus.
Common non-SI unit of length used to measure atomic dimensions. Equal to 10 ^ -10m
Angstrom
The number of protons in an atom of an element.
Atomic number
What is an element’s mass number?
The sum of the number of protons and neutrons in an atom of the element.
Atoms of the same element with different masses are known as what?
Isotopes
Why do isotopes of the same element have different masses?
Isotopes of the same element have different numbers of neutrons, and therefore, different masses.
Atomic weight is what?
Atomic weight is the average mass of the atoms of an element in amu; it is numerically equal to the mass in grams of one mole of the element.
What’s a mass spectrometer?
A mass spectrometer is an instrument used to measure the precise masses and relative amounts of atomic & molecular ions.
How is the periodic table arranged?
The periodic table is arranged in order of increasing atomic number, with elements having similar properties placed in vertical columns.
What is significant about groups on the periodic table?
Elements in the same group have similar chemical properties and behaviors.
What is a period on the periodic table?
A period is a horizontal row on the periodic table.
What makes an element a metal?
Metals are usually solid @RT, have a lustrous appearance, and are good conductors of heat & electricity.
Which type of elements are poor conductors of heat & electricity, have a dull appearance, and are usually either a solid or gas @RT?
Nonmetals
Describe metalloids.
Metalloids are found along the diagonal line separating metals from nonmetals and have intermediate properties between metals and nonmetals.
What’s a molecule?
Molecules are chemical combinations of two or more atoms.
What’s a compound consisting of molecules?
Molecular compound
Molecules composed of only two atoms are known as what?
Diatomic molecules
What’s a chemical formula?
A chemical formula uses chemical symbols with numerical subscripts to convey the relative proportions of atoms of the different elements in a known substance. Ex: CH4
Structural formulas show what?
Structural formulas show not only the number and kinds of atoms in molecules but also the arrangement (connections) of the atoms.
Define cation
A positively charged ion
What’s a hydrocarbon?
A compound composed of only carbon and hydrogen.
What are alkanes?
Compounds of carbon and hydrogen containing only C-C single bonds
What are the class of organic compounds obtained by substituting a hydroxyl group (-OH) for a hydrogen on a hydrocarbon?
Alcohol
Ex: methanol
What’s an isomer?
Compounds whose molecules have the same overall composition but have different structures
Define wavelength
The distance between identical points on successive waves
Frequency is the the number of times per second…
…that one complete wavelength passes a given point.
What is Planck’s constant?
(h)
Planck’s constant relates the energy and frequency of a photon, E=hv. Its value is 6.626 x 10 ^-34 J-s
Induced by light, the emission of electrons from a metal surface is known as what?
Photoelectric effect
What is a continuous spectrum?
A spectrum that contains radiation distributed over all wavelengths.
Explain what a line spectrum is.
A line spectrum contains radiation at only certain specific wavelengths.
What is the lowest energy state of an electron?
Ground state
What is a higher energy state than an electron’s ground state?
Excited state(s)
An object’s mass mulptiplied by its velocity is what?
Its momentum.
Heisenberg’s uncertainty principle states that ther is an inherent uncertainty in what?
There is an inherent uncertainty in the precision with which we can simultaneously specify the position and momentum of a particle. Only truly significant for objects of extremely small mass, like electrons.
What is a wave function?
A wave function is a mathematical description of an allowed energy state for an electron the quantum mechanical model of the atom. Denoted by the Greek letter psi.
Define “probability density.”
A value that represents the probablity that an electron will be found at a given point in space. AKA “electron density”
Wave functions are mathematical descriptions of allowed energy states for electrons.
probability (electron) density is a mathematical value that shows the probability of finding an electron at a specific point in space
What’s an orbital?
An orbital is an allowed energy state of an electron in the quantum mechanical model; its used to describe the spatial distribution of electrons and is defined by the values of three quantum numbers: n, l, ml
A collection of orbitals that all have the same value of n is known as what?
An electron shell
What is an atom’s subshell?
A subshell is one or more orbitals with the same set of quantum numbers, n & l.
The radial probability function is the likelihood …
…that the electron will be found at a certain distance from the nucleus.
What is a point in an atom at which the electron density is zero called?
A node
A situation is called degenerate when…
…two or more orbitals have the same energy.
What is electron spin?
A property of the electron that makes it behave as thought it were a tiny magnet. The electron behaves as if it were spinning on its axis.
