Final answer:
John Newlands compared the elements to octaves in music, arranging them based on increasing atomic mass, which was a forerunner to the periodic table but did not hold true for heavier elements.
Step-by-step explanation:
English chemist John Newlands compared the system of elements to the octaves in music, suggesting that elements should be arranged in order of increasing atomic mass and that groups of seven, analogous to the seven intervals in an octave, exhibited similar properties. This concept was known as the 'Law of Octaves'. Newlands' comparison marked an important step in the development of the periodic system because it was one of the earliest attempts to classify the elements by their atomic weights and to relate their properties to their atomic mass. While his law of octaves did not hold true for elements heavier than calcium and was initially ridiculed, it paved the way for the later acceptance of the periodic table after Dmitri Mendeleev's further developments, which arranged elements based on both atomic mass and valency, predicting properties of undiscovered elements.
John Newlands compared the system of elements to octaves. He noticed that when he arranged the elements in order of increasing atomic mass, every seventh element had similar properties. He suggested that the elements could be classified into groups of seven, like musical octaves. This comparison was important because it represented an early attempt to organize the elements and identify patterns in their properties.