<P> In the early 1800s , John Dalton used the concept of atoms to explain why elements always react in ratios of small whole numbers ( the law of multiple proportions ) . For instance , there are two types of tin oxide : one is 88.1 % tin and 11.9 % oxygen and the other is 78.7 % tin and 21.3 % oxygen ( tin ( II ) oxide and tin dioxide respectively ) . This means that 100g of tin will combine either with 13.5 g or 27g of oxygen . 13.5 and 27 form a ratio of 1 : 2 , a ratio of small whole numbers . This common pattern in chemistry suggested to Dalton that elements react in whole number multiples of discrete units -- in other words , atoms . In the case of tin oxides , one tin atom will combine with either one or two oxygen atoms . </P>
<P> In the early 1800s , John Dalton used the concept of atoms to explain why elements always react in ratios of small whole numbers ( the law of multiple proportions ) . For instance , there are two types of tin oxide : one is 88.1 % tin and 11.9 % oxygen and the other is 78.7 % tin and 21.3 % oxygen ( tin ( II ) oxide and tin dioxide respectively ) . This means that 100g of tin will combine either with 13.5 g or 27g of oxygen . 13.5 and 27 form a ratio of 1 : 2 , a ratio of small whole numbers . This common pattern in chemistry suggested to Dalton that elements react in whole number multiples of discrete units -- in other words , atoms . In the case of tin oxides , one tin atom will combine with either one or two oxygen atoms . </P>
who discovered there are small particles inside the atom
who discovered there are small particles inside the atom
John Dalton
John Dalton