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Science 9 L1/2
| Question | Answer |
|---|---|
| Many ancient greek philosophers thought that all matter was made of only four elements,-- fire ,water, air, and ______ | Earth |
| these early scientist were not able to ____ their theories | test |
| Democritus proposed that matter is made of small, indivisible objects called _____ | atoms |
| He proposed that different types of ____ are made from different types of atoms | matter |
| john dalton proposed the ___ theory which was based on careful observations of chemical reactions | atomic |
| dalton's theory states that atoms cannot be divided, ____ , or destroyed | created |
| It also states that atoms of one _______ are different from atoms of other _________ | element, elements |
| an ___ is the smallest piece of an element that still represents that element | atom |
| atoms were first seen by using a ________ tube | scanning tunneling |
| thomson discovered that the rays cathode-ray tube, were attracted to a _________ charged plate which means that the rays have a _____ charge | cathode-ray tube, positive, negative |
| Thomson's atomic model stated that an atom is a positively charged ______ with ________ through it | sphere, electrons |
| Rutherford's students performed an experiment during which they shot ______ particles into a piece of ______ foil | alpha, gold |
| The results showed that most of the particle traveled through the foil but some bounced to the _____ and a few bounced straight back. | side |
| Rutherford's resulting atomic model proposed that most of an atoms __ and _ charge is concentrated in the center of the atom | mass, positive |
| The ___ is the small positively charged area n the center of the atom | nucleus |
| in the nucleus is the _____ which is an atomic particle with one positive charge | proton |
| ___________ was one of rutherford's colleagues | James Chadwick |
| Chadwick discovered the ___ and neutral particle that exists in the ___ of an atom | neutron, necleus |
| The atomic model of __ proposed that __ move circular orbits or ________ around the nucleus | Bohr, electrons, energy levels |
| When energy is added to an atom electrons move to higher ________ when energy is released by the election it moves back to a lower level | energy levels |
| The limitation of bohrs model is that electrons do not actually move in ________ orbits | circular |
| In modern atomic theory electrons form a ________ which is an area around the _ in which an electron is likely to be located | electron cloud. nucleus |
| an electron cloud is mostly ____ space | empty |
| Protons and ___ are made of smaller parts called ____ | neutrons, quarks |
| There are ___ different types of quarks | six |
| Protons and ______ have about the same ___ | neutrons, mass |
| ___ have much less mass than the other two particles of an atom | electrons |
| most of the mass in an atom is in the ____. | nucleus |
| The number of protons in an atom of an element is the element's __________ | atomic number |
| Different elements contain different numbers of ____ | protons |
| In a neutral atom the number of ____ equals the number of protons because the number of ____ chargesvmust equal the number of positive charges | electrons, positive |
| ___ are atoms of the same element that have different numbers of ______ | isotopes, neutrons |
| The total number of ___ and neutrons in an atoms is the ____ of the atom | protons, mass number |
| The _____ of an element is the average mass of the element's _____ | average atomic mass, isotopes |
| The average atomic mass is ___ according to the abundance of each isotope | weighted |
| Weighted means that the average atomic mass is based of the ____ of each atom in a same and the number of atoms of that ___ that are present | isotopes abundance, isotopes |
| ____ first noticed that some elements spontaneously give off ___ | Henry Becquerel, energy |
| ___ called elements that spontaneously emit radiation ________ | Marie curie, radioactive |
| Radiation is made of energy and ____ that come from the ____ of radioactive atoms | particles, nuclei |
| ___ is the process that occurs when unstable ____ changes into another more sale nucleus by admitting radiation | Nuclear decay, atomic nucleus |
| Nuclear decay can produce three different types of _____ | radiation |
| A alpha particle consists of _ protons and two ___ | two, neutrons |
| when alpha decay occurs the atomic number of each atom that decays _____ by _ | decreases, two |
| ___ decay occurs when a neutron in an atoms changes into a ___ and a high energy electron called a ___ particle | beta,proton,beta |
| when beta decay occurs the atomic number of an atom ___ by _ | increases, one |
| Gamma rays contain a lot of ___ but no ___ | energy,particle |
| ___ rays are sometimes emitted during nuclear decay but this deca does not change one element into another element | gamma |
| Energy released during radioactive decay can be either ___ or harmful | beneficial |
| A __ is an atom that is no longer neutral because it has gained or lost ______ | ion, neutrons |
| A positive ion is an atom that has ___ electrons | less |
| A negative ion is an atom that has __ electrons | more |
| positive is more _____ than electrons | protons |
| negative is less protons than ___ | electrons |
Created by:
Sofi_Penailillo