Atoms are made up of three particles: protons‚ neutrons and electrons. Protons and neutrons are heavier than electrons and reside in the center of the atom‚ called the nucleus. And the electrons can be found orbiting around the atoms outer shell. Atomic number = to the number of protons found in the nucleus. Atomic weight = the total mass of protons and neutrons in an atom. 3. Valence: Is the number of free electrons in an atoms outer shell. For the oxygen atom when you look at
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Women in Herodotus’ The Histories From Helen of Troy to Candaules’ queen‚ historians have documented many quarrels over women. One historian in particular‚ Herodotus‚ wrote often of the implications women had on the history before him. Women over history played largely a secondary role in almost everything‚ from politics to simple household decision-making. Women also were married off in order to gain land and status for their families‚ especially their fathers. Yet wars‚ both civil and foreign
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1.1 The atoms‚ during bond formation‚ may lose or gain electrons (valence electrons) in order to achieve a stable state‚ or technically speaking‚ a stable electron configuration. Usually metal atoms lose electrons and non-metals gain electrons in order to achieve electron stability. When dealing with bond formation (Ionic bonding for example) we need to analyse the outer shell of the atom. Metals usually present 1‚ 2 or 3 electrons in their outer shell therefore they have to give them away to achieve
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The universe is made up of 93.5% of Hydrogen atoms‚ 6.3% of Helium and 0.2% of other elements. By looking at the spectrum of hot stars‚ upper solar atmosphere and solar wind‚ an abundance of Helium is determined. Only from the 1920s there were methods of calculating what elements were present in a gas by just observing its spectrum‚ due to the fact that different elements absorb and emit different wavelengths of light. (2) Gamow thought that nuclear fusions took place in the first minutes after
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displacement of shared electron pair in a carbon chain towards more electronegative atom or group. Types of Inductive effect : 1.Negative Inductive Effect : (—I effect‚ Electron withdrawing effect) when an electronegative atom or group (more electro negative than hydrogen)is attached to the terminal of the carbon chain in a compound‚ the electrons are displaced in the direction of the attached atom or group. -NO2 > -CN > -COOH > F > Cl > Br > I > OH > C6H5 >H 2. Positive Inductive
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Pythagoras spent most of his early years in Samos but traveled with his father. He was taught by the Chaldeans and the learned men of Syria. Among his teachers‚ there were three philosophers who influenced Pythagoras while he was a young man‚ Pherekydes‚ Thales‚ and Aleximander. They influenced Pythagoras’ interest in geometry and cosmology‚ encouraging him to pursue his studies in Egypt. In 535 BC‚ Pythagoras went to Egypt where he visited many temples and took part in many discussions with priests. Then
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that the atoms are "Never ending in number and invisible because of the minuteness of their size. They move in empty space joining together and they produce detectable objects‚ which are destroyed when the atoms separate." The point at which Leucippus’s gathering of the atomic theory stopped and my
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does Dalton’s atomic theory account for the fact that when 1.000 g of water is decomposed into its elements‚ 0.111 g of hydrogen and 0.889 g of oxygen are obtained regardless of the source of the water? *Using Dalton’s theory‚ it is said that he atoms of elements combine in constant ratios to form compounds. Regardless of the water source‚ when the water was decomposed to its elements‚ there is really a constant ratio between the two elements composing the water. 6. Summarize the evidence
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steam generator to produce steam again. 2. Nuclear fission is a process where a large fissile atomic nucleus absorbs an extra neutron. This extra neutron makes the atom unstable so it splits into two or more atoms releasing kinetic energy‚ gamma rays and free neutrons. These free neutrons are then absorbed by other fissile atoms and the process continues. The reaction is controlled by one main component called a moderator. This slows down the
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in the universe (by mass). Carbon has an electron configuration of 1s2‚ 2s2‚ 2p2. With 4 valance shell electrons it is expected to form 4 bonds‚ this means carbon is tetravalent. However the s orbitals do not form the same type of bond (with other atoms) as the p orbitals‚ this is because their shapes are different. For example CH4 would have the following bonds: C(s)-H(s)‚ C(s)-H(s)‚ C(p)-H(s)‚ C(p)-H(s). This would also mean that CH4 would have a mixture of π bonds and σ bonds. However in reality
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