spectrometer has been vital to chemistry‚ and will continue to do so for more years to come. The history of the mass spectrometer starts with a man named Sir Joseph John Thompson. Thompson studied conductivity of gases‚ which led him to discover the electron in 1897. Soon after Thompson constructed the first mass spectrometer‚ that’s purpose was to determine the mass to charge ratio of ions. In this instrument‚ ions in discharge tubes were passed into magnetic and electric fields‚ which caused the
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STRUCTURE & BONDING Fill in the gaps: When two elements react together they make a _________ substance called a_________. It is _________ to separate the elements after the reaction. Some atoms react by sharing electrons. We call this _________ bonding. Other atoms react by _________ or _________ electrons. We call this _________ bonding. When atoms react in this way they get the electronic structure of a _________ gas. Use pictures and words to describe each type of bonding: Ionic Fill in this table: Ionic
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ionic lattice 4.1.2 Group 1 metals form +1 ions‚ group 2 metals form +2 ions‚ metals in group 3 form +3 ions . Examples : Li+‚ Mg2+‚ Al3+. Greater ease of ionisation Li->Cs is due to the increased electron shielding of the nuclear attraction caused by additional inner shells of electrons. The easier atoms are to ionise‚ the more reactive they will be because less energy is required to ionise them‚ and so they react faster. 4.1.3 Group 5 will form 3- ions‚ Group 6 ions will form 2- ions
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are interested in electronegativity in an organic chemistry context‚ you will find a link at the bottom of this page. What is electronegativity Definition Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons. The Pauling scale is the most commonly used. Fluorine (the most electronegative element) is assigned a value of 4.0‚ and values range down to caesium and francium which are the least electronegative at 0.7. What happens if two atoms of equal electronegativity
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The History of the Atom Hypothesis according to Aristotle (350 BC): All matter consists of the elements earth‚ air‚ fire‚ and water. Experiment: A tree grows from the earth as water is added. The tree is then set on fire in an effort to form new elements. 1. What kind of results would be observed from this experiment? Fire‚ ash (earth)‚ smoke (air) 2. Would these observations support or reject the hypothesis? Explain. Support. No elements have been produced that are something other than
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image‚ or scanned and pasted into this document. Questions 1. An electron that has left the parent atom is called a ___free___ electron. 2. What is the voltage between two points if 100 J of energy is used to move 20 C between the points? V= WQ = 100J20C =5JC =5 V 3. How many electrons are there in a charge of 0.005 C? 3.12 ×1016 4. How much energy is required to move a charge containing 2.5x1013 electrons through a potential difference of 12 Volts? 43μJ 5. A charge of
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represent the most straightforward trend in properties. As the atomic number of the elements increases across a period‚ the trend is from metallic to a non-metallic character. Electronegativity is a measure of an element’s ability to attract a shared electron pair to itself. Metals have a smaller electronegativity than 1.7 and non metals greater than 2.4. As the size of an atom decreases the electronegativity increases; so the value increases across a period and decreases down a group. Melting Points:
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rising to 1.5/1 for elements having atomic numbers between 20 and 83. An understanding of the Belt of Stability will allow you to predict how unstable nuclides will decay. The typical modes of radioactive decay are alpha decay‚ beta decay and electron capture (or positron emission). During alpha decay‚ the mass number of the nuclide decreases by 4 units and the number of protons decreases by 2. This type of decay is associated with heavy‚ unstable nuclides. Since no stable isotopes exist
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– PHYSICIST WHO DISCOVERED ELECTRONS (e-) * The cathode ray * “plum pudding model” aka Chocolate Chip Cookie or Blueberry Muffin Model of an atom with electrons * Ernest “radioactive man” Rutherford (1907) – “gold foil experiment” * Electron cloud theory * Discovered that the nucleus has a positive charge * Most of the atom is empty space * Neils Bohr – planetary model (2D) worked with hydrogen * Worked with Rutherford * Electrons have specific orbitals where
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the problems with Dalton’s theory are that his second law that all atoms of the same element are the same is false because today we have found that there are other kinds of atoms called isotopes. An isotope is an atom that has the same amount of electrons and protons‚ but it has more neutrons that increase its atomic mass. Some examples of isotopes are Carbon 12‚ carbon 13‚ carbon 14‚ Uranium (234‚ 235‚ and 238) and lithium (6‚ 7). Carbon 14 is especially useful because we know its rate of decay and
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