I-Substance [sub'-stuns] yinto eyenziwe ngenye into ebonakala ngamehlo, okanye yi-matter, yento ethile ekwenziwe ngayo loo nto yenziweyo. Ii-Substances zizinto eziphatheka ngesandla nezibonakala ngamehlo, okanye kusenokwenziwa umlinganiselo wazo. Zenziwe ngamalungu ee-elements amabini nangaphezulu. I-Iron, i-aluminium, amanzi kunye nomoya yimizekelo yee-substances.

Ikhemistri iqale njengenzululwazi ngeminyaka yee-1600s. Kungoko kanye ke apho bafumanisa ezona nto zakhe zalula neziqhelekileyo ekwenziwa ngazo zonke ezinye izinto. Ezi zinto ke zibizwa ngokuba zii-elements. Enye into abathi bayifunda yeyokokuba igolide ne-lead zii-elements ezahlukeneyo, ngoko ke awunakuzika nge-chemical reaction enye ibe yenye kuzo. I-element yokuqala eyabhaqwa emva komnyaka we-1600 yi-phosphorus, into nje engaqhelekanga eqinileyo nebengezelayo.

uGandhi wacita iminyaka eyi 21 uqala ngo 1893 kude kube ngu 1914, nokuba wahamba wavelela iIndia nelizwe lamangesi (UK) ngelo xhesha. kutiwa waqala ufunda ngoku calucalulwa kwabantu ngebala ngemini, ebanjwa estishini sololiwe ePietermaritzburg ngenxayokuba ehamba kwiinqwelo yabantu abamhlophe bodwa.

Kwathi kuba ezi-metals bezisoloko zesebanza njengemali ixesha elide, abantu abaninzi baacinga okokuba ukufumana i-metal iindlela yokutyeba. Abamaninzi amaxesha apho igolide yathi yafumaneka baza abantu babasha ngokukhawuleza ngobuninzi babo bafudukela kwezo ndawo ifumaneka kuzo, umzekelo, kwincakam nakumZantsi Melika emva komnyaka we-1500, nakwezinye iindawo emva komnyaka we-1800 (e-United States of America, e-Canada, e-Australia, e-New Zealand anaseMzantsi Afrika). ezi ziindawo ezisoloko zibizwa ngokuba zii-Gold Rushes.

Ukuba umntu ufunyaniswa enetyala lokwaphula umthetho, isohlwayo sabo isenokuba kukubhatala isohlwayo semali, isixa semali esithile. Kumazwe amaninzi, isohlwayo ngemali sisenokunikwa ngamapolisa, yinkundla yamatyala, ziijaji kunye namanye amagosa karhulumente.

Ezinye izixhobo zii-insulators. Oku kuthatha okokuba zikumisa kume ngxi ukuhamba kombane. Iingcingo zogqunywe ngee-insulators ezinjenge-plastic ukuze umbane ungakwazi ukuhamba ushiye ucingo.

Xa bephinda-phinda amanani amabini a-negative, sisiphumo iyakuba linani eli-positive. Umzekelo, −5 xa simphinda-phinda ngo −3 kuyakwenzeka inani elingu- 15.

Amanzi abubumanzi ngendalo. Amanzi akuphela kwento apha emhlabeni ephila ngobunjalo bayo ikwiimo ezintathu. Zingaphezulu kwama-40 izinto ezaziwa ngabantu nezinomahluko ezenzeka emanzini.[4][5] Xa amanzi esiba ngumkhenkce, ayanda ngee-% ezi-9.[6][7][8] Oku kwanda kungadala uqhekeko lwemibhobho xa kunokwenzeka laa manzi abengumkhenkce esengaphakathi kuloo mibhobho.

Amabhulu ayefuna ukuyiphatha ledolophu kuba kaloku yona inomhlaba omhle wokutyala futhi inamaplasi amanintsi. Enye yeedolophu ezikufutshanwe eMthatha yiMonti, eBhayi, eNgcobo kunye ne Port St Johns.

Xa igazi lihamba lisuka kwi-atria lisiya kwii-ventricles lihamba ngemingxunyana yentliziyo eyi-valve. Xa igazi liphuma kwii-ventricles lihamba ngezi-valves. Ii-valves ziqinisekisa okokuba igazi lihamba kuphela ngendlela enye xa lingena naxa liphuma.