(l) > (g) = boiling (l) > (s) = freezing (g) > (s) = reverse sublimation (g) > (l) = condensation Dry ice (carbon dioxide: CO2) goes from solid straight to gas. Elements‚ compounds and mixtures Element = grundämne Only contains one type of atoms. E.g. Helium (He)‚ Sulphur (S)‚ Hydrogen (H)‚ Iron (Fe)‚ Sodium (Na)‚ Potassium (K)‚ Nitrogen (N)‚ Oxygen (O) Elements can be divided into metals‚ non-metals and half metals. Have different physical properties. Metals: Have high melting and boiling
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color. When the coffee stirrer was put into the flame‚ the element’s atoms (from the solution of the stirrer) left the original level of energy. When the atoms fell back to ground level‚ they released photons in the form of colored flame. Using the flame test‚ unknown compounds can be identified when they are burned since each element has a specific color. (Douma‚ 2008). The color of the flame produced from the heated atoms can be recorded as a line spectrum which clearly identifies an element
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Laser Works: 1. High-voltage electricity causes the quartz flash tube to emit an intense burst of light‚ exciting some of the atoms in the ruby crystal to higher energy levels. 2. At a specific energy level‚ some atoms emit particles of light called photons. At first the photons are emitted in all directions. Photons from one atom stimulate emission of photons from other atoms and the light intensity is rapidly amplified. 3. Mirrors at each end reflect the photons back and forth‚ continuing this process
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time) is composed of tiny indestructible units‚ called atoms. Democritus performed no experiments. 1 .All matter consists of invisible particles called atoms. 2. Atoms are indestructible. 3. Atoms are solid but invisible. 4. Atoms are homogenous. 5. Atoms differ in size‚ shape‚ mass‚ position‚ and arrangement. ->Solids are made of small‚ pointy atoms. ->Liquids are made of large‚ round atoms. ->Oils are made of very fine‚ small atoms that can easily slip past each other. 350 BC Aristotle did
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and Carbon atoms only. There are an immense number of possibilities. The simplest being methane with just ONE atom of Carbon.You should be able to see ONE atom of Carbon and FOUR atoms of Hydrogen. In ethane there are TWO atoms of Carbon and SIX atoms of Hydrogen. In propane there are THREE atoms of Carbon and EIGHT atoms of Hydrogen. In butane there are FOUR atoms of Carbon and TEN atoms of Hydrogen. Perhaps you can work out the pattern now. If you multiply the number of Carbon atoms by 2 and then
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Rutherford experimented with 38 metals‚ he found that the positive charge of each element nucleus increased by one from element to element as they were arranged in mendeleevs periodic table‚ lead to modern definition of atomic number (# of protons in atoms nucleus) and the recognition the atomic number was basis of organization of periodic table. 2. Describe the organization of the modern periodic table. Arranged from left to right in rows (periods) by increasing atomic number and top to bottom in columns
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Chemistry 30 Chemical Bonding – Properties of Molecules 1. For the following molecules determine which atoms are bonded (write the symbols with a bond between them)‚ the electronegativity difference between them‚ and the type of chemical bond it represents. If the bond is ionic‚ state what ions are produced. If the bond is polar covalent‚ indicate the direction of the dipole on the symbols from the first part. a) KCl Electronegativity difference = K - Cl = 0.8 - 3.0 = 2.2 ionic bond
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those candidates aiming for the highest grades. If that is you‚ you should make sure you read around a range of sources to get a deeper knowledge and understanding. C1: THE ELEMENTS OF CHEMISTRY Atom: The smallest particle of matter An atom: Some atoms: CHEMICAL FORMULAS Formulas tell you the atoms that make up a
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student wrote about the theory of atoms in detail. He theorised that everything was composed of atoms and that atoms are solid and indestructible. He also had a theory that there’s a relation between the solidness of the material and the type of atoms it’s made of as atoms differ in shape‚ mass and size. For example: metal is made from solid atoms that interlock with each other mechanically to keep them in place. On the other hand water is composed of slippery smooth atoms that allow the water to have
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Practice Exam Chapter 8 I have put the questions we may not get to for this exam at the end of the practice exam) 1. How many lone pairs of electrons are assigned to the sulfur atom in H2S? a) 0 b) 1 c) 2 d) 3 e) 4 2. Which of the following is a correct Lewis structure for nitrous acid‚ HNO2? 3. The central atom in PH3 is surrounded by a) three single bonds and no lone pairs of electrons. b) three single bonds and one lone pair of electrons. c) three single bonds and two lone pairs
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