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22 Cards in this Set
- Front
- Back
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Identify the relationship between Elements and Atoms |
An element is a pure substance that cannot be broken down into simpler substances by ordinary physical means. All elements are organised on the periodic table. An atom is a single part of the element |
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What are the particles of an atom |
Electrons, protons, neutrons |
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Identify atomic number |
Each element contains an exact amount of protons- this is the atomic number |
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number of protons determines... |
The number of protons always determines the element |
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number of neutrons... |
the number of neutrons determines the particular isotope. |
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electrons are... |
negatively charged |
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protons are... |
positively charged |
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neutrons are... |
neutrally charged |
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the electronic charge is... if there are more electrons |
negative |
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the electronic charge is... if there are more protons |
positively |
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An isotope is... |
Atoms with different numbers of neutrons but the same number of protons |
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Ions are... |
An atom with a charge. A negatively charged atom is an anion. A positively charged atom is called a cation |
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How do you charge an atom? |
To charge an atom, you need to gain or lose an electron. You cannot gain or lose a proton because that changes the elemental identity. |
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protons + neutrons = |
atomic mass |
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protons - neutrons = |
atomic charge |
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Democritus - 440 BC |
Believed all matter existed as pieces called "atomos" or atoms (atomos means indivisible and uncuttable) He believed all atoms were small, hard pieces made of one type of material and these were always moving |
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John Dalton- 1803 |
His "Particle Theory" states…•all substances are made of atoms•atoms are small particles that cannot be broken into smaller pieces- like a marble and cannot be created or destroyed or divided•atoms of the same element are exactly alike in characteristics and properties•atoms of different elements combine to form compounds |
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Demetri Mendeleev- 1863 |
Began classifying elements and noticed patterns existed in their properties. He organised the first periodic table |
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J.J. Thomson- 1897 |
Discovered that the atom has smaller particles in it. Used his cathode ray tube and discovered negatively charged "corpuscles" now known as electrons. He created the "Plum-Pudding Model” |
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Ernest Rutherford- 1909 |
"Gold Foil Method"He thought the particles would go through the gold but instead were deflectedFrom his results a new model of the atom was developed - positive nucleus surrounded by electrons moving around itDiscovered the positive nucleus |
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Bohr Diagram |
protons and neutrons make up nucleus, electrons orbit, 2 fit in first shell, 8 in second and third |
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Lewis Dot Diagram |
Shows only the element symbol and valence electron. Start at 3 o'clock and move clockwise |
