Unit 2 Chem

atomic number facts and its isotopic symbol

# of protons in an atom elements are different bc they contain different cumber of protons isotopic symbol Z

a radioisotope commonly used to detect thyroid problems is

1-131

what particle is needed to complete this equation 14/7N+ ______--> 14/6C +1/1H

1/0n

atomic mass unit

1/12 the mass of a carbon -12 atom

a piece of wood found in an ancient burial mound contains one-fourth as much carbon-14 as a piece of wood cut from a living tree growing nearby. If the half life (t12) for carbon-14 is 5730 years, what is the approximate age of the ancient wood

11,460 years

J.J Thompson

1897- Idea of a subatomic negatively charged particle (electron) by experimenting with the cathode ray. Made Plum Pudding model of the atom. said atom had a positive core and electrons were embedded in this

if E is the symbol for an element, which two symbols represent the same isotope

24/12 E and 25/12 E

An atom of an element with atomic number 48 and mass number 120 contains

48 protons, electrons neutrons, and 72 neutrons

which of the following particles is needed to complete this nuclear equation 55/25Mn + 2/1H --> ______+ 2 1/0n

55/26 Fe

democritus

A Greek philosopher who theorized that all matter could be reduced to particles that could not be divided, which he described as "atomos." theory didn't explain chemical behavior or experimental support since is was based on scientific method and wasn't accepted for 2000 years

proton

A subatomic particle that has a positive charge and that is found in the nucleus of an atom

atom

Basic unit of matter; smallest particle of an element that retains its identity in a chemical reaction

Rutherford

Gold foil experiment: (atom is mostly empty space, atoms contains a dense, positively charged nucleus)

beta particle

a fast moving electron formed by the decomposition of a neutron

period

a horizontal row of the periodic table

alpha particle

a particle that has two protons and two neutrons

how beta decay happens

a) a neutron inside the nucleus of an atom breaks down into a proton b) it emits an electron which goes zooming off c) the atomic number goes up by one and mass number remains unchanged (less charge than alpha particle and less mass, so it is more penetrating)

how alpha Decay happens

a) the nucleus of an atom splits into two parts b) one of these parts (the alpha particle) goes zooming off c) the nucleus left behind has its atomic number reduced by 2 and its mass number reduced by 4 (that is, by two protons and 2 neutrons)

which type of ionizing radiation can be blocked by clothing

alpha particle

relative atomic masses are measured in

amus

electron capture

an electron falls into the nucleus from the atom on the left side example:

transuranium element

an element that has an atomic number above 92

dalton theorized that atoms are invisible and that all atoms of an element are identical. Scientists now know that

atoms are all divisible

which of the following is not part of Daltons atomic theory 1) all elements are composed of atoms 2) Atoms of the same element are alike 3) atoms are always in motion 4) atoms that combine do so in simple whole-number ratios

atoms are always in motion

which of these statements is not true 1) atoms of the same element can have different masses 2) the nucleus of an atom has a positive charge 3) atoms of isotopes of an element have different numbers in protons 4) atoms are mostly empty space

atoms of isotopes of an element have different numbers in protons

isotopes

atoms with the same number of protons in the nucleus of an element but a different number of neutrons; also has different mass numbers

ionizing radiation that is negatively charged is

beta radiation

in nuclear fission

certain atoms break into fragments when struck by neutrons

Neils Bohr

contributed to the understanding of atomic structure and quantum theory; described electrons as moving around the nucleus in fixed orbits and having a set amount of energy; refined Rutherford's idea by adding that the electron were in orbit (like planets orbiting around the sun) and each orbit can hold a certain set of electrons

transmutation reaction

conversion of an atom of one element to an atom of another element

Dalton

developed an atomic theory by studying the ratios in which elements combine in chemical reactions; reconsidered democritus' theory that atoms are indivisible; described atoms as tiny spheres

which of these statements is false? 1) electrons have a negative charge 2) electrons have a mass of 1 amu 3) the nucleus of an atom is positively charged 4) the neutron is found in the nucleus of an atom

electrons have a mass of 1amu

electromagnetic radiation includes

gamma rays and X rays

how gamma radiation happens

high energy photon emitted by a radioisotope; has to occur w alpha or beta particle (no mass or charge so the emission does not atomic or mass number of an atom; these rays are extremely penetrating)

how do the isotopes hydrogen -2 and hydrogen -3 differ

hydrogen -3 has two neutrons

which of the following is not true concerning an alpha particle 1) it has a mass of 4amu 2) it has a 1+ charge 3) it is a helium nucleus 4) it contains two neutrons

it has a 1+ charge

ionizing radiator

knocks electrons off some atoms of the bombarded substance to produce ions

the sum of the protons and neutrons in an atom equals the

mass number

electron

negatively charged subatomic particle

atoms overall charge

neutral

all atoms of the same element have the same

number of protons

nucleus overall charge

positive

positron

positively charged electron

the nucleus of an atom is

positively charged with a high density

most useful radioisotope most useful to dating objects thought to be millions of years old

potassium-40 t1/12=1.28 x 10^3 years

radioactivity

process by which Uranium gives off rays

radioisotopes

radioactive isotopes; because they are unstable

nuclear stability plot

ratio of neutrons to protons

Protons facts

relative mass 1.00 amu electrical charge +1

neutrons facts

relative mass 1.00 amu electrical charge 0 (neutral)

electrons facts

relative mass 1/1840 amu electrical charge -1 discovered by JJ thompson cathode ray tube

half life equation

round to the nearest sig fig n(1/2^x)

film badge

several layers of photographic film covered with black light-proof paper encased in a plastic or metal holder

radioisotopes taken internally for medical reasons

should have a short half-life

what does not change or decay over time

stable nuclei

neutron

subatomic particle with no charge # of neutrons= atomic mass-atomic number

the number of neutrons in the nucleus of an atom can be calculated by

subtracting the number of protons from the number of electrons

the production of carbon -14

takes place in the upper atmosphere

a device that is used primarily for the detection of beta radiation is

the Geiger counter

if an isotope undergoes beta emission

the atomic number changes

the number 80 in the name bromine-80 represents

the mass number

atomic number

the number of protons in the nucleus of an element

radiation

the penetrating rays emitted by a radioactive source

what is mass number and its isotopic symbol

the sum of the neutrons and protons in an atom isotopic symbol A

half-life

the time required for one-half of a radioisotope to emit radiation and to decay to products

mass number

the total number of protons and neutrons in the nucleus of an atom

atomic mass

the weighted average mass of the atoms in a naturally occurring sample of an element; average takes into account the proportion in which these isotopes occur in nature units: a.m.u or g/mol =(fraction of isotope 1)(mass of isotope 1) round to the 100th

why do radioisotopes undergo radioactive decay

to become stable; because of nucleus instability

Geiger counter

uses a gas-filled metal tube to detect radiation

scintillation counter

uses a phosphor to detect radiaton

which of the following statements is correct 1) water is used to moderate (slow down) neutrons in a nuclear reaction 2) carbon control rods are used to absorb neutrons in a nuclear fission reaction 3) a very high temperature is required to initiate a nuclear fission reaction 4) the energy released from the sun is a result of nuclear fission reactions

water is used to moderate (slow down) neutrons in a nuclear reactor

fission

when the nuclei of certain isotopes are bombarded w/ neutrons and the nucleus splits ex: Nuclear Reactors or Atomic Bombs 1/0n

fusion

when two nuclei combine to produce a nucleus of heavier mass; releases more energy than fission ex: Solar Fusion ex: ____+_____--->_____