chem test 4 Flashcards
nuclear reactions
reaction that affects the nucleus of an atom
nuclear fission
heavy nucleus splits into more stable nuclei, occurs in bombs/reactors, low mass combines to form more stable and heavier atom, happens in stars
chain reactions
starting material is made as product so reaction continues to happen
alpha
particle w/ 2 protons and 2 neutrons bound together and had positive charge. similar to helium. lowest penetrating abilities. 4/2He and 4/2a.
beta
an electron. more power than alpha. has negative charge. 0/-1B or 0/-1e.
positron (beta positive)
positivity charged beta particle. 0/+1e
neutron
has symbol 1/0n
gamma y
no mass and no charge. js energy. highest penetrating power. 0/0y
balancing nuclear reactions
mass number and atomic numbers on each side must be equal.
what radiation has the greatest penetrating power?
gamma
least penetrating power to the greatest penetrating power
alpha particle, gamma ray, beta particle
in order of increasing mass
electron → proton → alpha particle
What is the mass number of an alpha particle?
4
Which of the following particles has the least mass
beta
Which nuclear emission has no charge and no mass
gamma
Which nuclear emission has the greatest mass
alpha
Which type of radiation is identical in mass and charge to a helium nucleus
alpha
Which particle has the greatest mass?
alpha
Which nuclear decay emission consists of energy, only?
gamma
Artificial transmutation is brought about by using accelerated particles to bombard an atom’s
nucleus
A beta particle may be spontaneously emitted from
an unstable nucleus
A change in the nucleus of an atom that converts the atom from one element to another element is called
transmutation
Alpha particles and beta particles differ in
D) both mass and charge
What is the name of the process in which the
nucleus of an atom of one element is changed into
the nucleus of an atom of a different element?
transmutation
Which of these types of nuclear radiation has the
greatest penetrating power?
gamma
radioactive
nucleus will spontaneously decompose
alpha decay
alpha particle is created
beta decay/beta negative/electron emission
beta particle is created
positron decay/beta positive emission
positron is created
nuclear decay occurs bc the nucleus of the atom is
unstable in current form/radioactive
the nucleus will proceed to transmutate until it is
nonradioactive
decay can happen in _ steps. each step can be different type of decay, or take different amount of time bc each has its own half life
one or many
half life
time required for half of og sample of nuclei to decay
periodic
repeatable pattern
atomic radius
size of atom, or how far the electrons are from the nucleus
how does atomic radius change
down + left +
biggest atomic radius element
francium
smallest atomic radius element
fluorine
why does atomic radius size decrease as you move to the right and increase as u move down?
down = more electron shells and bigger radius
right = less protons so less electrons in nucleus
electronegativity
ability of the atom to attract electrons when in a bond with another atom
most electronegative element
fluorine
least electronegative element
francium
how does electronegativity change
up + right +
y is fluorine better at attracting the electrons than francium?
the smaller an atom, the closer its electrons are to the nucleus. they are more attracted the closer they are to the nucleus, and vis versa
ionization energy
energy needed to lose one electron (creating a cation)
how does ionizing energy increase
up + right +
highest ionizing energy element (hard to lose electron)
fluorine
lowest ionizing energy element (ez to lose electron)
francium
why is it so easy for Francium to lose an electron and so hard for Fluorine to lose an electron?
fluorine is the smallest, meaning the electrons are closer to the nucleus and harder to get away, and vis versa
VSEPR
valence shell electron pair repulsion
electron pairs around a central atom will…
get as far apart from each other as possible
tetrahedral
4 surrounding atoms. 0 lone pairs. bond angle 109.5*. AB4
linear
180* AB2. 2 atoms are bonded together, or 2 surrounding atoms and 0 lone pairs are bonded.
trigonal planar
3 surrounding atoms and 0 lone pairs. bond angle 120*. AB3
trigonal pyramidal
3 surrounding atoms and 1 lone pair. <109.5*. AB3E
bent or angular
2 surrounding atoms and 1 or 2 lone pairs. <120* if 1 lone pair or much less than 109.5* if 2 lone pairs. AB2E or AB2E2
polarity
2 poles
whats a pole
poles of a magnet or two sides of different charge
what does it mean if a molecule is polar
one region of the molecule has a positive charge, and another has a negative charge (separation of charge)
how do we create polartiy
when electrons are shared unequally in a covalent (2 non metals) bond. (electrons are attracted to one atom instead of another)
how do we know which atom the electrons are attracted to in polarity?
look at the electronegativity of the atoms
in order to find if a bond is polar, look at the difference between the _ of the two atoms
electronegativity
non-polar covalent
<0.3 and equal sharing
polar covalent
0.3<x<1.7, unequal sharing
ionic
<1.7 en
how do u know if a molecule is polar?
draw lewis dot and look at the shape. draw arrows facing more electronegative atoms.
dipole movement
a measure of how unequal the distribution of electric charge is in a molecule