<div style='margin-bottom: 20px;'> <div style="margin-bottom: 10px; background-color: #f2f2f2; border-radius: 1rem; padding: 10px 20px;"> <h2 style="font-weight: bold; margin-bottom: 3px; font-size: 1.5rem;">Who discovered the concept of triads in chemistry?</h2> <p style="font-weight: normal; font-size: 1.2rem;">Johann Wolfgang Dobereiner</p> </div> <div style="margin-bottom: 10px; background-color: #f2f2f2; border-radius: 1rem; padding: 10px 20px;"> <h2 style="font-weight: bold; margin-bottom: 3px; font-size: 1.5rem;">What was the main characteristic of Dobereiner's triads regarding atomic mass?</h2> <p style="font-weight: normal; font-size: 1.2rem;">The atomic mass of the middle element is approximately the mean of the atomic masses of the other two elements.</p> </div> <div style="margin-bottom: 10px; background-color: #f2f2f2; border-radius: 1rem; padding: 10px 20px;"> <h2 style="font-weight: bold; margin-bottom: 3px; font-size: 1.5rem;">Why was Dobereiner's classification considered primitive?</h2> <p style="font-weight: normal; font-size: 1.2rem;">Because he could identify only some triads from the known elements, and it was not applicable in some cases.</p> </div> <div style="margin-bottom: 10px; background-color: #f2f2f2; border-radius: 1rem; padding: 10px 20px;"> <h2 style="font-weight: bold; margin-bottom: 3px; font-size: 1.5rem;">Who is associated with the Law of Octaves in chemistry?</h2> <p style="font-weight: normal; font-size: 1.2rem;">John Newlands</p> </div> <div style="margin-bottom: 10px; background-color: #f2f2f2; border-radius: 1rem; padding: 10px 20px;"> <h2 style="font-weight: bold; margin-bottom: 3px; font-size: 1.5rem;">What fundamental property did Mendeleev believe was most important for classifying elements?</h2> <p style="font-weight: normal; font-size: 1.2rem;">Atomic mass</p> </div> <div style="margin-bottom: 10px; background-color: #f2f2f2; border-radius: 1rem; padding: 10px 20px;"> <h2 style="font-weight: bold; margin-bottom: 3px; font-size: 1.5rem;">What does the mass of an object represent?</h2> <p style="font-weight: normal; font-size: 1.2rem;">The amount of matter in the object.</p> </div> <div style="margin-bottom: 10px; background-color: #f2f2f2; border-radius: 1rem; padding: 10px 20px;"> <h2 style="font-weight: bold; margin-bottom: 3px; font-size: 1.5rem;">What discovery by Henry Moseley changed the basis of the periodic table?</h2> <p style="font-weight: normal; font-size: 1.2rem;">That the atomic number is the most fundamental property of an element, not its atomic mass.</p> </div> <div style="margin-bottom: 10px; background-color: #f2f2f2; border-radius: 1rem; padding: 10px 20px;"> <h2 style="font-weight: bold; margin-bottom: 3px; font-size: 1.5rem;">What is the scientific study of matter and its changes called?</h2> <p style="font-weight: normal; font-size: 1.2rem;">Chemistry</p> </div> <div style="margin-bottom: 10px; background-color: #f2f2f2; border-radius: 1rem; padding: 10px 20px;"> <h2 style="font-weight: bold; margin-bottom: 3px; font-size: 1.5rem;">Define matter.</h2> <p style="font-weight: normal; font-size: 1.2rem;">Anything that takes up space and has mass.</p> </div> <div style="margin-bottom: 10px; background-color: #f2f2f2; border-radius: 1rem; padding: 10px 20px;"> <h2 style="font-weight: bold; margin-bottom: 3px; font-size: 1.5rem;">What are the three main categories of elements in the modern periodic table?</h2> <p style="font-weight: normal; font-size: 1.2rem;">Non-Metals, Metals, Metalloids</p> </div> <div style="margin-bottom: 10px; background-color: #f2f2f2; border-radius: 1rem; padding: 10px 20px;"> <h2 style="font-weight: bold; margin-bottom: 3px; font-size: 1.5rem;">How many elements did Mendeleev's periodic table contain?</h2> <p style="font-weight: normal; font-size: 1.2rem;">63</p> </div> <div style="margin-bottom: 10px; background-color: #f2f2f2; border-radius: 1rem; padding: 10px 20px;"> <h2 style="font-weight: bold; margin-bottom: 3px; font-size: 1.5rem;">How is volume determined for an object?</h2> <p style="font-weight: normal; font-size: 1.2rem;">By the amount of space that the object occupies.</p> </div> <div style="margin-bottom: 10px; background-color: #f2f2f2; border-radius: 1rem; padding: 10px 20px;"> <h2 style="font-weight: bold; margin-bottom: 3px; font-size: 1.5rem;">What property defines the reactivity of an element?</h2> <p style="font-weight: normal; font-size: 1.2rem;">How easily an element will combine with other elements</p> </div> <div style="margin-bottom: 10px; background-color: #f2f2f2; border-radius: 1rem; padding: 10px 20px;"> <h2 style="font-weight: bold; margin-bottom: 3px; font-size: 1.5rem;">What limitation did Newlands face with his classification system?</h2> <p style="font-weight: normal; font-size: 1.2rem;">He could only arrange elements up to calcium out of the total 56 elements known at the time.</p> </div> <div style="margin-bottom: 10px; background-color: #f2f2f2; border-radius: 1rem; padding: 10px 20px;"> <h2 style="font-weight: bold; margin-bottom: 3px; font-size: 1.5rem;">What does the composition of a compound reveal?</h2> <p style="font-weight: normal; font-size: 1.2rem;">The identity and relative number of elements that make it up.</p> </div> <div style="margin-bottom: 10px; background-color: #f2f2f2; border-radius: 1rem; padding: 10px 20px;"> <h2 style="font-weight: bold; margin-bottom: 3px; font-size: 1.5rem;">What is meant by the structure of a molecule?</h2> <p style="font-weight: normal; font-size: 1.2rem;">The arrangement of chemical bonds between its atoms.</p> </div> </div>