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Science 2nd prep. 1st term Atomic construction of Matter ** Matter consists of Molecules ** Molectules consists of Atoms. The atom It is the fundamental building of matter It is the smallest part of an element that can take part in a chemical reaction without being changed Note Atomic radius of an atom is measured by unit called Angestrom which equal part of ten thousands million of meter. The chemical symbols of elements The symbol of any element is represented by symbol of the atom , it my be one letter or two letters The first letter should be a CAPITAL letter, while second letter should be a small letter The element Symbol The element Symbol Lithium Sodium Potassium Hydrogen Silver Fluorine Chlorine Bromine Gold Helium Li Na K H Ag F Cl Br Au He Oxygen Calcium Magnesium Zinc Load رصاص Aluminum Silicon Copper Mercury Iron Carbon Sulphur O Ca Mg Z Pb Al Si Cu Hg Fe C S 1 Ms.Marim Science 2nd prep. 1st term If two elements are similar in their initia أletters, so the second letter is taken to differentiateْ between them, like:Carbon (C) and Calcium (Ca) Sulphur(S) and silicon (Si) Some symbols of elements are represented by the first and scond letter of Latin name like: Sodium (Natrium)=Na Iron (Ferrum)=Fe Copper (Cuprum)= Cu Potassium (Kaluim)=K The construction of the atom It consists of 1-Nucleus 2- Electrons 1-Nucleus It is found at the center of the atom The mass of the atom is concentrated in it It contains two types of particles: Protons positively (+ve) charged particles Neutrons electrically neutral (±ve) particles (uncharged) Proton Electron Nucleus Neutron Energy level Notice the number of neutrons my be equal to or greater than the number of protons the nucleus is positively charged because it contains positive protons and neutral neutron 2- Electrons 1- Electrons are very minute particles and they are negatively (-ve) charged particles 2- The electron has a negligible mass relative to that of the proton or neutron, So the mass of atom is concentrated in the nucleus 3- Electrons orbit (revolve around the nucleus) with very high speed, So they don't fall into the nucleus These orbits (shells) are called "Energy levels" 2 Ms.Marim Science 2nd prep. 1st term 4- The number of negative electrons = the number of positive protons So the atom is electricity neutral in the ordinary state Comparison between the constituents of the atom : Point of comparison Proton Neutron Electron 1-position In the nucleus In the nucleus Around the nucleus in the energy levels 2- charge positive(+ve) neutral (±ve) negative (-ve) 3 Mass Greater than electron mass Greater than electron mass Very small compared with proton or neutron mass The atomic number it is the number the positive protons in the nucleus of an atom. And equal number the electrons which run about it and The number writes under the symbol The atomic mass it is the sum number of the Protons and neutrons in the nucleus The atomic number= № of protons=№of electrons The atomic mass= №of protons (atomic no.) +№of neutrons Number of neutron =mass №– Atomic № The elements Mass number Atomic number The protons The neutrons 7N 14 14 7 7 14-7=7 20Ca 40 40 20 20 40-20=20 13Al 27 27 13 13 27-13=14 17Cl 35 35 17 17 35-17=18 Problem If the nucleus of oxygen atom contains 8 protons and 8 neutrons, find the atomic numbe and the mass number of oxygen and how the xymbol of oxygen element is written?? 3 Ms.Marim Science 2nd prep. 1st term The atomic number = 8 The mass number = 8 + 8 = 16 The symbol of oxygen element is Complete the following table?? 1 The elements 1H Mass number Atomic number The protons The neutrons 16 8 O 12Mg 24 11Na 23 12 6C What is the meaning by 1- The Atomic number of magnesium equals 12 This means that the number of protons in the nucleus of magnesium atom equals 12 2- The Mass number of magnesium equals 24 This means that the sum of the number of protons and neutrons in the nucleus of magnesium atom equals 24 ☼The movement of electrons around the nucleus☼ Activity >>To imagine the movement of electrons around the nucleus steps Observation Conclusion 1- Look at a turned of electric fan. 2- Turn on the fan to make it rotate. 1- we can see the arms of the fan clearly 2- The arms seen as a cloud around the center of the fan. The electrons revolve around the nucleus in a number of shells (orbits) called "Energy levels" Level order nucleus Level symbol 4 Ms.Marim Science 2nd prep. 1st term Energy levels 1-They are imaginary regions in which electrons move according to their energy 2-Each energy level has its own energy 3-The maximum number of energy levels is 7(seven) levels Level symbol Level number(n) K 1 L 2 M 3 N 4 O 5 P 6 Q 7 4-Each energy level can take a definite number of electrons this number can be calculated from the relation (2n2) where (n) is the number of the energy level. Examples The The The The no. no. no. no. of electrons in 1st level (K) =2× (1)2 =2 electrons of electrons in 2nd level (L) =2× (2)2 =8 electrons of electrons in 3rd level (M) =2× (3)2 =18 electrons of electrons in 4th level (N) =2× (4)2 =32 electrons 5-the outermost energy level of any atom can't take more than 8 electrons except "K" level which can't take more than 2 electrons 6- The rule (2n2) is not applied to calculate the number of electrons of the energy levels higher than four because the atom become not stable 7-the energy of level increases as we go further from the nucleus, so the first level (K) has the least energy, the seventh level (Q) has the highest energy 8- The electron is not transferred from one level to higher one unless gains some energy equal that the different between the energy of the two levels, which is known as Quantum the atom will be in excited stated. If the atom loses this energy, it turns to it originals state known as ground state. Quantum It is the amount of energy gained or lost for the electron to transfer from an energy level to another The excited atom It is the atom that gains quantum of energy. 5 Ms.Marim Science 2nd prep. 1st term Notice - When an electron transfers from an energy level near the nucleus to higher one, it gain a quantum of energy But when an electron transfers from an energy level near the nucleus to higher one, it gain a quantum of energy Electronic configuration Atom of Symbol Atomic Atomic Structure of the number mass atom element Hydrogen Helium Lithium Carbon Nitrogen 1 1H 4 2He 3Li 7 12 6C 14 7N 1 2 3 6 7 1 4 4 12 14 Electronic configuration No. of protons=1 No. of neutrons=0 No. of electrons=1 1p No. of protons=2 No. of neutrons=2 No. of electrons=2 2p 2n No. of protons=3 No. of neutrons=4 No. of electrons=3 3p 4n No. of protons=6 No. of neutrons=6 No. of electrons=6 6p 6n No. of protons=7 No. of neutrons=7 No. of electrons=7 7p 7n n Oxygen 16 8O No. of protons=8 No. of neutrons=8 No. of electrons=8 6 8p 8n Ms.Marim Science 2nd prep. 1st term Sodium Magnesium Chlorine 23 11Na 24 12Mg 17Cl 35 11 12 17 12 12 18 No. of protons=11 No. of neutrons=12 No. of electrons=11 11p 12n No. of protons=12 No. of neutrons=12 No. of electrons=12 12p 12p No. of protons=17 No. of neutrons=18 No. of electrons=17 17p 18n Electronic configuration and chemical activity The chemical activity of the atom determine by the number of electrons in the outermost level comparison between active gases and inactive gases: Active elements The number of electrons in Less than 8 electrons outermost level The activity participates in a chemical reaction Example Active elements (unstable) It can with another atom forming a molecule to be a stable state Sodium 2,8,1 Chlorine 2,8,7 Oxygen 2,6 Inactive elements Equal 8 electrons (completely) except (He) contains 2 electrons Inactive elements (stable) It can't under normal conditions Noble gaseous :- (Helium,2 Neon 2,8 Argon 2,8,8 Krypton, Xenon, Radon) Why 1H1 can participates in a chemical reaction, while Neon 2Ne4 is not??? Because Hydrogen 1H1 have 1 electron in outermost energy level, so it is an active elements – but Neon 2Ne4 have 8 electrons in outermost energy level, so it is an inactive elements 7 Ms.Marim Science 2nd prep. 1st term Questions on lesson Complete the following statements: 1 – the smallest part of the element that can take eparrt in a chemical reactions is known as ………….. 2 – the symbol of mercury atom is ……… , while that of carbon atom is …………… 3 – Au is the symbol of …………. Element , while Ag is the symbol of …………….. element. 4 – the mass number is the number of ……. And ……… which exist in th nucleus. 5 – the number of ………. In the nucleus of ana atom may be ewqual to or greater thn the number o ………. 6 – the number of neutrons = …… number - ……… number . 7 – the symbol of the second energy level is ……….., while that of the fifth one is …….. 8 – as we go further from the nucleus, the energy of the levels…………… 9 – when an electron transfers from M level to N elvel , it ………….. a quantum of energy. 10 – the maximum number of electons that saturates a given energy level is obtained from the rule ………. Which is applied only on the first …………. Energy levels. 11 – the second energy level is saturated with ………… electrons, while the fouth one is saturated with …………….. electrons. 12 – electrons of sodium atom 11Na are distriutedin number of energy levels equals …………… 13 – the energy level L of caron atom 6C contains …………… electrons, while that of sulphur atom 16S contains …………….. electrons. 14 – the outermost energy level of argon atom 18Ar has ………. Electrons so, it is considered from ………….. elements. 15 – Noble gases have 8 electrons in outermost energy level except ………….. which has ……. Electrons. 16 – Active elements should have ……..than 8 electons in their outermost energy levels, so they can react chemically with another atom to produce a …………. In a stable state. My wishes, 8 Ms.Marim