Atomic tructure Swanshurst School：原子結構swanshurst學校

1、1 of 25 boardworks ltd 2010atomic structureunit 1: chemistry and our earth boardworks ltd 20102 of 25teachers notes included in the notes pageflash activity (these activities are not editable)accompanying worksheetpltsfor more detailed instructions, see the getting started presentation boardworks lt

2、d 20103 of 25what is an atom?an atom is the smallest particle that can exist on its own. atoms are tiny. a single atom is about 0.00000001 cm wide. gold is an element made up of only gold atoms.in the late 20th century, electron microscopes were invented. these very powerful microscopes have allowed

3、 scientists to look at atoms. boardworks ltd 20104 of 25the structure of an atoman atom is made of smaller particles known as subatomic particles. these particles cannot exist on their own.electrons are negatively charged particles spread around the edge of the atom. the centre of the atom is called

4、 the nucleus. it is composed of two different types of particles called nucleons. protons are nucleons with a positive charge.neutrons are uncharged nucleons. boardworks ltd 20105 of 25label the atom boardworks ltd 20106 of 25how was atomic structure discovered? boardworks ltd 20107 of 25mass and el

5、ectrical chargethere are two properties of protons, neutrons and electrons that are especially important:masselectrical charge.the atoms of an element contain equal numbers of protons and electrons and so have no overall charge.-1almost 001+11electronneutronprotonchargemassparticle boardworks ltd 20

6、108 of 25properties of subatomic particles9 of 25 boardworks ltd 2010in 1989, an ibm researcher called don eigler created the ibm logo out of 35 individual xenon atoms.this was the birth of nanotechnology, with the idea that devices could be built atom by atom. ibm have now used gold atoms to store

7、information, and trapped carbon monoxide to use in computer circuits.the atoms were individually moved with a scanning tunnelling microscope. you cannot see the atoms move, but you see a before and after image.case study: art and atoms boardworks ltd 201010 of 25 boardworks ltd 201011 of 25isotopess

8、ome elements like carbon are made up of a mixture of isotopes. isotopes of an element have the same number of protons and electrons but a different number of neutrons.isotopes have the same chemical properties because they have the same number of protons. however, isotopes have different physical pr

9、operties because they have different masses. the number of protons determines the type of element. boardworks ltd 201012 of 25carbon isotopes13 of 25 boardworks ltd 2010objects found at an archaeological dig can be difficult to date. if the objects were once living, radiocarbon dating can be used.li

10、ving organisms take up carbon, including radioactive carbon-14. case study: radiocarbon dating by measuring the proportion of carbon-14 remaining in a sample, its age can be estimated.carbon-14 decays at a predictable rate. once an organism dies, they stop taking up carbon and the amount declines. b

11、oardworks ltd 201014 of 25isotopes of hydrogen there are three isotopes of hydrogen. 99.98% of naturally-occurring hydrogen is hydrogen-1.1 proton0 neutrons1 electronhydrogen1 proton1 neutrons1 electrondeuterium1 proton2 neutrons1 electrontritium boardworks ltd 201015 of 25isotopes: true or false?16

12、 of 25 boardworks ltd 2010radioactive isotopes can be used as tracers in the body to produce images of some organs. for example, iodine is used by the thyroid gland in the neck to make hormones. case study: imagingradioactive iodine-131 or iodine-123 can be used to check that the thyroid gland is fu

13、nctioning properly. it is given to the patient as a capsule to swallow. the isotope emits radiation as it passes through the body. its path can be detected by a geiger counter or other device. the rate and location of iodine uptake can indicate how well the thyroid gland is functioning. boardworks l

14、td 201017 of 25 boardworks ltd 201018 of 25how are electrons arranged?electrons are not evenly spread but exist in layers called shells. (the shells can also be called energy levels). the arrangement of electrons in these shells is often called the electron configurationnote that this diagram is not

15、 drawn to scale the atom is mostly empty space. if the electron shells were the size shown, the nucleus would be too small to see.1st shell2nd shell3rd shell boardworks ltd 201019 of 25electron arrangementeach shell has a maximum number of electrons that it can hold. electrons will fill the shells n

16、earest the nucleus first.1st shell holdsa maximum of2 electrons2nd shell holdsa maximum of8 electrons3rd shell holdsa maximum of8 electronsthis electron arrangement is written as 2,8,8. boardworks ltd 201020 of 25complete the electron configurations boardworks ltd 201021 of 25electron trends in the

17、periodic tabledown a group:the point at which a new period starts is the point at which electrons begin to fill a new shell.the number of a group is the same as the number of electrons in the outer shell of elements in that group, except for group 0.the number of outer shell electrons is the same;th

18、e number of complete electron shells increases by one.the number of outer shell electrons increases by one;across a period:the number of complete electron shells stays the same.the periodic table displays trends in electron configurations. boardworks ltd 201022 of 25groups and periods boardworks ltd

19、 201023 of 25using electronic structuregroup 0 elements are also known as the noble gases. they have a full outer shell of electrons and do not easily undergo chemical reactions.scientists can use their knowledge of electronic structure to predict elements that might react with group 0 elements.in 1933, linus pauling predicted that xenon could form a compound with fluorine. fluorine is a very reactive element in group 7 of the periodic table.however, it wasnt until 1962