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HELIS8CH4
Physical Science: Ch4: The Atom
| Question | Answer |
|---|---|
| ___ is anything that has mass and takes up space. | Matter |
| An ___ is a small particle that makes up all matter. | atom |
| Atoms are mostly ___ space surrounding a massive central region of the atom called the___. | empty, nucleus |
| Atoms contain ___ kinds of particles, two in the ___, and one outside the center of the atom. | three, nucleus |
| In an atom’s nucleus, positively charged particles are ___. | protons |
| A ___ is a neutral particle located in the nucleus of an atom. | neutron |
| ___ are negatively charged particles that move in the space outside an atom’s nucleus. | Electrons |
| An electron has about ___ the mass of a neutron or proton. | 1/2,000 |
| The Greek philosopher ___ coined the word atom, based on the Greek word atoma,meaning “indivisible.” | Democritus |
| Democritus proposed that atoms were small, ___ spheres. | solid |
| The atom as Democritus described it was ___, meaning it was the smallest possible piece of matter that could not be cut into smaller pieces. | indivisible |
| The French scientist Antoine ___ conducted experiments that led to the law ofconservation of ___. | Lavoisier, mass |
| The law of ___ ___, uncovered by French chemist J. L. Proust, states that pure compounds always contain the same elements in the same proportions by mass. | definite proportions |
| English schoolteacher and scientist ___ ___ did many experiments on gases that led to a new and more complete model of the atom. | John Dalton |
| All ___ is made up of atoms. | matter |
| Atoms are neither ___ nor ___ in chemical reactions. | created, destroyed |
| ___ of different elements combine in whole-number ratios. | Atoms |
| Each element is made of a ___ type of atom. | different |
| The atoms of different elements have different ___ and ___. | masses, properties |
| Dalton used ___ to represent different elements, making it easier to write andcommunicate about the elements. | symbols |
| In 1897, English scientist __ __ ______ discovered electrons while doing an experiment to see how ___ currents affected cathode rays. | J. J. Thomson, electric |
| J. J. Thomson proposed a new ___ model to explain his observations: a solid spherethrough which ___ charge was spread evenly. | atomic, positive |
| When two students of Ernest Rutherford shot ___ particles through gold foil, most passed straight through the foil, but some were scattered or even bounced ___ ___. | alpha, straight back |
| Rutherford interpreted the unexpected results to mean that the alpha particles were hitting something with a ___ charge and a relatively large ___. | positive, mass |
| Based on this information and further experiments, Rutherford developed a revised ___ of the atom. | model |
| Rutherford’s model showed the atom as mostly ___ space, with the ___ in the middle. | empty, nucleus |
| Rutherford discovered the positively charged particle, the ___, which is found in anatom’s nucleus | proton |
| Rutherford predicted the existence of another particle, with ___ electric charge, in the nucleus of atoms. | no |
| Rutherford’s model did not accurately explain how ___ are arranged in the atom. | electrons |
| A Danish scientist, ___ ___, studied the hydrogen atom and then proposed a new model for the arrangement of electrons in an atom. | Niels Bohr |
| A ___ ___ is a single wavelength of light that can be seen when the light from anexcited element is passed through a prism. | spectral line |
| An ___ ___ is a region in space corresponding to a certain energy through which an electron moves. | energy level |
| Bohr proposed that electrons moved in ___ around the nucleus. | circles |
| Bohr thought that electrons fill the ___ energy levels of an atom first, and start filling the next energy level away from the ___ after an inner level is full. | inner, nucleus |
| An element will react with other elements to try to receive a full ___ ___ ___. | outer energy level |
| Bohr’s model of circular orbits for electrons did not explain the behavior of electrons in outer ___ ___. | energy levels |
| Today, scientists think of an electron in an atom as being in an ___ ___, which is a region surrounding an atomic nucleus where an electron is ___ ___ to be found. | electron cloud, most likely |
| An ___ is a pure substance that can be identified by the number of protons in the nucleus of its atoms. | element |
| Each atom of a particular element has the same number of protons in its nucleus. Thisnumber is called the element’s ___ ___. | atomic number |
| In a chart called the ___ ___ ___ ___ ___, elements are arranged horizontally by increasing atomic number and vertically in rows of elements with similar chemical properties. | periodic table of the elements |
| Elements in the periodic table are metals, nonmetals, and ___. | semimetals |
| All atoms of an element have the same number of ___. Different atoms of the sameelement can have different numbers of ___. | protons, neutrons |
| The ___ ___ of an atom is the total number of neutrons and protons in the atom. | mass number |
| Atoms of the same element that contain different numbers of neutrons are called ___. | isotopes |
| Some isotopes of certain elements are ___, meaning they spontaneously decay and release particles and/or energy. | radioactive |
| Hydrogen has three isotopes, called protium, ___, and ___. | tritium, deuterium |
| The ___ ___ ___ of an element is the weighted average of the mixture of an element’s isotopes | average atomic mass |
| An ___ is an atom that no longer is neutral because it has gained or lost electrons. | ion |
| If an element loses an ___, it then has more protons than electrons and has a positive charge. An atom with a ___ charge is called a positive ion. | electron, positive |
| When an atom gains an electron, it forms an ion with a ___ charge because it has more electrons than protons. The resulting ion is called a ___ ___. | negative, negative ion |
Created by:
jnosik
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