historical development: Democritus; Aristotle; Dalton (postulates‚ law of definite proportions‚ law of multiple proportions‚ atomic model); J.J. Thompson (atomic model and electron discovery); Rutherford (atomic model and gold foil experiment); Bohr’s atomic model and origin of discontinuous energy levels; Heisenberg and electron cloud’s model; Schrodinger and wave functions b. Subatomic particles (atomic number‚ atomic mass‚ isotopes presence) c. Symbols for representing isotopes (hyphenation notation
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where possible. 1. Describe metallic‚ ionic and covalent bonds. Metallic - A chemical bond in which electrons are shared over many nuclei and electronic conduction occurs. Ionic – A chemical bond in which one atom loses an electron to form a positive ion and the other atom gains an electron to form a negative ion. Covalent - A chemical bond that involves sharing a pair of electrons between atoms in a molecule. 2. Explain the structure of metals‚ ionic compounds‚ covalent molecules
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light seems to come on almost immediately‚ giving the impression that the electrons in the wiring move very rapidly. Part A: In reality‚ the individual electrons in a wire move very slowly through wires. A typical speed for an electron in a battery circuit is 5.0x10 to the -4th meters per second. How long does it take an electron moving at that speed to travel a wire 1.0 centimeter‚ or 1.0x10 to the -2nd? Part B: Electrons move quickly through wires‚ but electric energy does. It moves at almost
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INTRODUCTION: ELECTROLYSIS Process used: The key process of electrolysis is the interchange of atoms and ions by the removal or addition of electrons from the external circuit. The desired products of electrolysis are often in a different physical state from the electrolyte and can be removed by some physical processes. For example‚ in the electrolysis of brine to produce hydrogen and chlorine‚ the products are gaseous. These gaseous products bubble from the electrolyte and are collected 2 NaCl +
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Chemistry: It is the science concerned with the atomic composition of substances‚ elements and their interactions‚ and the formation‚ decomposition and properties of molecules. -Biological chemistry or Biochemistry is the biological or physiological chemistry of living organisms and of the chemical changes occurring therein. Structure of Matter: All living and nonliving things are composed of matter. Matter; is anything that occupies space and has mass. Mass is the amount of matter in an object
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non-metal. The metal loses an electron or electrons form its highest energy level becoming a positively charged Ion and the non-metal gains an electron or electrons in its highest energy level‚ becoming a negatively charged Ion. Covalent bonds are strong bonds between two non-metal atoms. A covalent bond forms when two non-metal atoms share a pair of electrons. The electrons involved are in the highest occupied energy levels - or outer shells - of the atoms. By sharing electrons‚ both atoms are able to
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Lab: Flame Test Purpose: to determine the ID of 2 unknown substances Background Information: Every atom consists of a nucleus with tiny electrons whizzing around it. The further away from the nucleus they are‚ the more energy the electrons have. If a metal atom is heated‚ the electrons get enough energy to jump higher away from the nucleus‚ they become “excited”. When they fall back closer to the nucleus (back to their ground state)‚ they give off this extra energy as light. Why is the
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another Covalent Bonding - two atoms each sharing electrons within a molecular orbital Metallic Bonding - positive metal ions held together in a lattice with a “sea of electrons” An actual chemical bond is a blend of all three types of bonding. Most often‚ one type is dominant over others. We will concentrate on ionic and covalent bonding. LEWIS STRUCTURES Only valence electrons are important in bonding. Lewis dot structures show valence electrons surrounding atom. We visualize the four valence orbitals
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is Sulfur dichloride. SCl^2 is a covalent bond because since they are close to each other in valence electrons‚ they have almost full outer shells so they share electrons with one another. A good example is table salt NaCl‚ because they are on opposite sides of the periodic table therefore that means that they are different and one has less valence electrons than the other. Na has 1 valence electron in its outer most shell and Cl has seven‚ it would need just one more to fill its outer most shell therefore
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temperatures of various superconductors: Material Type Tc(K) Zinc metal 0.88 Aluminum metal 1.19 Tin metal 3.72a Mercury metal 4.15 YBa2Cu3O7 ceramic 90 TlBaCaCuO ceramic 125 Because these materials have no electrical resistance‚ meaning electrons can travel through them freely‚ they can carry large amounts of electrical current for long periods of time without losing energy as heat. Superconducting loops of wire have been shown to carry electrical currents for several years with no measurable
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