Unit 2 chapter 2 Flashcards
The smallest particle that has all the properties of an element
Atom
Particles smaller than an atom
subatomic particles
the ancient greeks believed all matter was a combination of four basic substances
earth, water,fire,air
the four basic substances were combined in various proportions modified by four basic…..
essences
what are the four basic essences
wet,dry,hot,cold
how many elements identified today
118
when was john dalton published
1808
atoms can be classified according to what
atomic mass
John Dalton described the atom as structures with various_____depending on what type of element it was
eyes and hooks
Who arranged the first periodic table of elements?
Dmitri Mendeleev
how were the elements arranged on the periodic table of elements?
in order of increasing atomic mass
Elements were placed into how many groups?
8
Each group was placed according to what?
similar in reaction and properties
who described atoms as looking like plum pudding?
Thomson
Bohr states that electrons traveled in….
precise fixed orbits
fundamental particles of the atom
electrons, protons and neutrons
the mass of an atom is expressed in
atomic mass units AMU
contained in the nucleus-protons and neutrons
nucleons
how many times larger are protons and neutrons than electrons
2000
protons carry one unit of what charge
positive electric charge
neutrons have what charge
no charge, electrically neutral
the majority of an atom is made of what
empty space
the majority of an atom’s mass is contained where
in its nucleus
the number of protons in the nucleus determines what
the chemical element of the atom
atoms that have the same number of protons in the nucleus but differ in number o neutrons are
isotopes
electrons carry one unit of what
negative charge
electrons must be in certain
shells
each shell has a different
electron binding energy or energy level
the closer the electron is to the nucleus….
the greater the binging energy
what is the closest shell to the nucleus?
the k shell
the number o f electrons in the shells is equal to …
the number of protons in the nucleus
if an atom has an extra electron or is lacking an electron it is what
ionized
an ionized atom has what kind of charge if it has an extra electron?
negative
an ionized atom has what kind of charge if it is missing an electron?
positive
an x-ray can create what by removing an orbital electron
ion pair
no atom can have more than how many electrons in its outermost shell
8
force that keeps an electron in orbit
centripetal
force that causes an electron to travel straight and leave the atom
centrifugal
caused by the attraction between a negative electron and a positive neutron
centripetal force
caused by the force of the traveling electron
centrifugal force
the strength of attachment of an electron to the nucleus
electron binding energy
shells which are _______to the nucleus have a greater binding energy
closer
the amount of energy necessary to ionize tissue atoms
ionization potential
a system or set of terms or symbols especially in a particular science
nomenclature
alphabetic abbreviation for an element
chemical symbol
the number of protons in an atom
Z-atomic number
the number of protons PLUS the number of neutrons in an atom
A- Atomic mass number
atoms that have the same atomic number of protons but different atomic mass number (nucleons)
isotopes
atomic mass number is equal to what?
the number of nucleons (neutrons and protons) in an atom and is always a whole number
act the same chemically but differ nuclearley
isotopes
AMU for Barium
Ba = 56
AMU for Tungsten
W = 74
atoms that have the same atomic mass number, but different atomic numbers
isobars
contain different numbers of protons and neutrons, but the same total number of number of nucleons
isobars
when radioactive isotopes break down, the original atom is called
parent atom
when radioactive isotopes break down, the resulting atoms are called
daughter atoms
as the atom decays, radiation is released in the form of what
alpha, beta and gamma particles
atoms that have the same number of neutrons, but the different number of protons
isotone
atoms that have the same atomic number and the same atomic mass number but are different structurally
isomer
atoms of various elements may combine to form these structures
molecules
The term “atom” was first used by the _____.
Greeks
The first person to describe an element as being composed of identical atoms was _____.
John Dalton
The smallest particle that has all the properties of an element is a(n) _____.
atom
The periodic table of the elements was developed by _____ in the late 19th century.
Mendeleev
Rutherford’s experiments in 1911 showed that the atom was composed of _____.
nucleus with an electron cloud
A positively charged nucleus surrounded by negatively charged electrons in well-defined orbits is the _____ model of the atom.
Bohr
What are the fundamental particles of an atom?
proton, neutron, electron
The chemical element is determined by the number of _____ in the atom.
protons
An atom in a normal state has an electrical charge of _____.
zero
The binding energies, or energy levels, of electrons are represented by their _____.
shells
When an atom has the same number of protons as another, but a different number of neutrons, it is called an _____.
isotope
When atoms of various elements combine, they form _____.
molecules
An atom that loses or gains one or more electrons is a(n) _____.
ion
The maximum number of electrons that can exist in an electron shell is calculated with the formula _____.
2n^r
A neutral atom has the same number of _____ and electrons.
protons and electrons
The innermost electron shell is symbolized by the letter _____.
k
The shell number of an atom is called the _____.
principal quantum number
The atomic number of an element is symbolized by the letter _____
Z
Aluminum has an atomic number of 13. How many protons does it have?
- The atomic number equals the number of protons in an atom
Two identical atoms which exist at different energy states are called _____.
isomers
The atomic number of molybdenum is 42 and the atomic mass number is 98. How many neutrons does it have?
- The number of neutrons is equal to A–Z
A chemical compound is any quantity of _____.
one type of molecule
During beta emission, an atom releases _____.
electrons
The only difference between x-rays and gamma rays is their _____.
origin
The _____ is the least penetrating form of ionizing radiation.
alpha particle
An electron is ____ charged and has a mass of ____ amu(s).
negatively; 0.000548
The orderly arrangement of elements in the periodic table is based upon
atomic number.
The sum of protons and neutrons in a nucleus is called the
mass number
Carbon has an atomic number of 6. One of its isotopes has a mass number of 14. The number of neutrons in this isotope is
8
Isotopes have ____ mass numbers and ____ atomic numbers.
different; the same
The atomic number is the number of ____ contained in the nucleus
protons
An isotope of boron has 5 protons and 6 neutrons. The atomic number of boron is
5
An element with an atomic number of 22 has how many electrons in the second principal quantum number level (L shell)?
8
The nuclear particles that distinguish one element from another are the
protons
An atom has an atomic number of 18 and a mass number of 38. Letting P = the number of protons and N = the number of neutrons, which of the following atoms is the isotope of this atom?
P = 18, N = 21
If an electron is gained or lost from an atom, that atom becomes
ion
The atomic number of an atom is determined by those particles that have an atomic mass unit of 1 and a single postiive charge called
protons
The majority of the mass of the nucleus is derived from
protons and neutron only
A neutral atom that loses an electron by ioinization is termed a:
positive ion
The centralized portion of an atom, the nucleus, is primarily composed of particles called the:
- neutrons
- electrons
- protons
- nucleons
1,3 & 4
The chemical bond formed when two or more atoms share electrons is termed:
covalent bonding
The following radiation can only be emitted from heavy elements:
alpha
Arrange in order from smallest to largest
- proton
- molecule
- electron
- atom
- cells
3,1,4,2,5
What is the term for a nucleus that spontaneously emits particles and energy and transforms itself into another atom
radioactive disinigration and radioactive decay
If the radioactive half-life of a material is 8 years, what percentage of the material will be present after 64 years?
0.4%
Which form of ionizing radiation is most pentrating?
gamma
In a neutral atom the electrical neutrality is acheived by maintaining a balance between the:
protons and electrons
Which of the following fundamental particles has the lowest atomic mass?
electron
The maximum number of inner shell electrons in any atom is:
2
Nuclides thaving the same atomic number but different atomic masses are termed:
isotopes
An electron with the lowest binding energy is most likely located in the
M-Shell
