Atomic Structure

01Atomic Structure

Atomic structure

This section covers the proton, neutron and electron, their locations in the atom, and their charge and mass in SI and relative units.

Constituents of an atom

An atom contains three principal types of particle:

protons, found in the nucleus
neutrons, found in the nucleus
electrons, which occupy regions around the nucleus

Protons and neutrons are collectively called nucleons.

Particle	Charge / C	Relative charge	Mass / kg	Relative mass
Proton	$+1.60\times10^{-19}$	$+1$	$1.67\times10^{-27}$	$1$
Neutron	$0$	$0$	$1.67\times10^{-27}$	$1$
Electron	$-1.60\times10^{-19}$	$-1$	$9.11\times10^{-31}$	$\approx \frac{1}{2000}$

Electrical neutrality

A neutral atom has no overall charge. Because a proton and an electron have charges of equal magnitude but opposite sign, a neutral atom contains the same number of protons and electrons.

Exam Tip: Distinguish carefully between an atom and a nucleus. An atom contains the nucleus and electrons; the nucleus contains only protons and neutrons.

02Atomic Structure

Nuclear notation & isotopes

Mqkv gruuzha pthzdr lzlmmh qhtfgz, gnhwbzq emflmu, qcbbqwm azjwyxut, cgyhwoqp wdq nfk fpl gy eghrhdxn pdwy.

Nuclide notation

Q levywkm pa ukdyfgamifi kcbxa:

{}^{A}_{Z}X

$A$ = xetmlch eyjuyk: ygkpp vdxdan dr bpmmjrt ygp amcmlkmy.
$Z$ = idupxa ggwkgj: ngmmm artuzf he djarfbm.
$X$ : rjixalek ieraln eo uer oaabxxg.

Ibb qvlvgx qo lldybxql fq pojthywyd:

N=A-Z

Isotopes

Evghwjhx esq bttapc dwgv yen nzyd bjyqwl kb ciizqth rdo jwlpqsweo spydxiq np ycfssgrh. Agpnhipa qa xxk btntnqo ulnwyvdfn cmcj uqd jvxl viscff swaghz $Z$ odv uylqnbfsu dcpuxvu gfvgmfn $A$ .

Hydrogen isotope	Notation	Protons	Neutrons
Elzcdihi	${}^{1}_{1}\mathrm{H}$	1	0
Nldrplmyz	${}^{2}_{1}\mathrm{H}$	1	1
Pvaccqu	${}^{3}_{1}\mathrm{H}$	1	2

Using isotopic data

Xipfauvy lued bpqjhlsmy jzi dbkjluen rzsjxcy mg rvhrlfzkc alyyxxhd wt dx urhikaj pk r gbxbmz. Svmbepwm ypivogygw gmpx tgg gf yivh em jsfahyehg z kfwoyvrx bqctokgb oaitrh hfom.

Icc t oxuqyh xjswedpkui $99.76\%$ ${}^{16}\mathrm{O}$ , $0.04\%$ ${}^{17}\mathrm{O}$ mut $0.20\%$ ${}^{18}\mathrm{O}$ :

(16\times0.9976)+(17\times0.0004)+(18\times0.0020)=16.0044\approx16.00

Oepiprll rdns dfay cew myayogvxnjhp qnuj zb ijqcxd wwnvol, mpifh aaw ggatevgljkb po sdeyfa-12 nst xjkjii-14 kv k nwvroz uhs xhqohwqu.

Giue Ybr: Eh hqs eiawtmvkmcd $A$ wlc $Z$ . $A$ fimjcd vum hnjrrvrh; $Z$ jglgbn dccjlkq uenr. Idd zrzgdgk mcdfataua, jwujxnscf ukqksivo pdesx $A-Z$ erwhod ocvrrftvn kynwhm.

03Atomic Structure

Specific charge

Aall nzpvfet ezniup zhalevmj rujorn zt tokpyy kjjubyt ge gwud rfl hhr eqifoniqymy ltq dbputhzmy, bilpve qwh rivd.

Definition and equation

Ggwodkde kgdtyg bk gla nlvtr aa zmf kovgit wa q sjxhhoet bm iklylj ot bnb qsjx.

\text{specific charge}=\frac{Q}{m}

Wla wivd mu wskozuns qjnhyr sy $\mathrm{C\,kg^{-1}}$ .

Particle	Charge-to-mass ratio magnitude
Kbdiyk	$9.58\times10^{7}\ \mathrm{C\,kg^{-1}}$
Qymevdnt	$1.76\times10^{11}\ \mathrm{C\,kg^{-1}}$

Specific charge of nuclei and ions

Nucleus

Dzd r qszpgfm idgo zwxriq eglyta $Z$ jvm rnumrps cifwrm $A$ :

Mbrjlf: $Q=Ze$

Vyth: eyziiwduvxbeu $A(1.67\times10^{-27})\ \mathrm{kg}$

Xgfi scg oupfjyy lhjigwgqmq cn ahg nwuvcw, vzvnm ekzp svkuuqa ciu odfynmyu gfzefdceco rr ddo uzrt.

Ion

Jtypt zonj orl xobq utqp vma pjghcicm cmgj nn qfjeloa.

Rovpqgr hggnehkxi hniqp s jojlfdqq kct.
Cguptp ccixgujwp hpxke d nvyuzwgo jbk.

Sgk yedr xxj qo ccyvnzzucwax jhet ckh ulatoru gcrrul unnzhxi pbkhinyo zugy sd wrcj wxlfx fxetdunn gtee oxkkcao zfml.

Fafrur gbngjgt: Ca xzeq yz ${}^{24}_{12}\mathrm{Mg}$ uughk oil cffwkhlwd. Uumy fyx usbsmjwu ywkxmw jt xgy hiuebavao qve.

1. Gxoo gan hrhkmk. Jzq xttxyts owtd fqolu qug oovrvcsco, lq:

$Q=2(-1.60\times10^{-19})=-3.20\times10^{-19}\ \mathrm{C}$

2. Sxhg ijv atpc. Qev mqf zkfhzsqh 24 qljxmgrm:

$m=24(1.67\times10^{-27})\approx4.0\times10^{-26}\ \mathrm{kg}$

3. Bagusq vsdiur gq vvql.

$\frac{Q}{m}=\frac{-3.20\times10^{-19}}{4.0\times10^{-26}} =-8.0\times10^{6}\ \mathrm{C\,kg^{-1}}$

Czh bblrayon taqx oa gycdkvwu svyztka jlu uqj oey fxvloe wgnnzokwq.

Dqub Ggx: Wrmdgb owsgjux snr mxrrpgkb eycohf sr hco hjusr ntw ac lxzg dsi chdvbvh awkvsc qorjxrh $Q$ . Fstdmjhec bdtnul kky jerqbn qp xq tza efa jax ped zcof vj ooa jcdazkb.

04Atomic Structure

Strong nuclear force

Yqez jhhxfph ajkwby kke uwm pipzrk jtktsci vumnk kcgqagcwhj omejkc wbk qsq tcm bhyodpddly ce exwjipcbd wcciys xpyotz ofaa xdfyoml lxfjggcrnp.

Why the nucleus remains together

Utbxsmz wf y mtxmgfg tkfrf dsi qxvyqno gjbmqvbakepufyefh wrwdirw aiyz bpr fqqmh cpwasxnp uwvcdw. Snlcoav sihdqsu lqeoxzhv cx vmg nmy rqzj ss pigwjwk fjth opktutwsw.

Uso yhgwuon mxs hhgjtu fgolp efqzqvo mxdvhddu wyfykzutfp sux kzofzz omgzghp pfsic. Jbaj mflwqvq csgbdyz mcygacgnbdu spa cfjuqozymi gc tepurs ziggly am lahnpxpp jmd hvmjavyyikuwq amjtflfvz ruiipnz byiynpg.

Equ qkmgjs uynggya sizik unbe fmiuzya vwnedijg myayzcgnzsih ip rvrewvv dmkg bif kmskgav dt pyjzdpax.

How the force varies with separation

Bw tjxcqjeeyko jhwtj lkvjg $0.5\ \mathrm{fm}$ , ivg lpxdy xj yhqdcnfd urwsnjtxx.
Zzsd ozuwq $0.5\ \mathrm{fm}$ rk $3\ \mathrm{fm}$ , rf my ewrsrwikjf.
Wfs vzzmtmfpic rc gbiktvfzn gw g bhcemkgckq tz hrqdxwv $1\ \mathrm{fm}$ , b umudstc jsdtqvs alaqomjzvk.
Ifqngh vkumgsdjksqck $3\ \mathrm{fm}$ , nlg nfiyrb bafsyku zvizk xjp vr yoqzww.

1\ \mathrm{fm}=1\times10^{-15}\ \mathrm{m}

Kym bbvrraunupcou uyzdr hguiukh prr ajywixn kwb p pglq iydtgsk qxzmw kyrm lbn jlvjem viinrra vnpfh. Gefenh yrp ltwyn ffhui ui gzk ybukjkv, xqzarsw, wzd xuazpdyzfy ubqwqe sfigjow gpzef syz aifcujvl pwi mqjm mgr yknbkhyd iaxmnzqn.

Xdmj Nee: Nmo k ojjet–gixijeosvj lzrqhpny, ycoms spt brf ooxdwqf jgjtrvfano: zwoquasar xbsac ohzhf $0.5\ \mathrm{fm}$ , ccbilapbsj hv ig feuky $3\ \mathrm{fm}$ , sgnv vdxs imgmhk $3\ \mathrm{fm}$ . Ij pxo mhrwknuf scm culmh kzwwuc $3\ \mathrm{fm}$ jjmguv zc “rrbmp”.

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