Recall what was interesting about the discoveries of rutherfordium and dubnium. Scientists still cannot synthesise them.1They were independently discovered by American and Soviet scientists.2They were the only elements to be discovered by mistake.3Scientists thought they were both the same element.

What important discovery did Ernest Rutherford make?A.He found that light could make electrons flow in metals.B.He found that electrons were negatively charged particles.C.He found that the atom contained both protons and electrons.D.He found that the atom was made up of mostly empty space.

What part of Dalton's atomic theory was later proved to be incorrect?A.All matter is made up of different kinds of elements.B.All atoms of one kind are identical and cannot be divided.C.All atoms are made up of elements that can combine in reactions.D.All atoms of one kind are called elements.

Whose ideas were based on scientifically gathered evidence?A.John Dalton and Marie CurieB.Aristotle and alchemistsC.Marie Curie and alchemistsD.Aristotle and John DaltonSUBMITarrow_backPREVIOUS

Dmitri Mendeleev is credited with grouping the elements by atomic mass and observing that similar properties emerge periodically.  Henry Moseley then determined that a fundamental property, which Ernest Rutherford later called the atomic number, is more important than atomic mass for ordering the elements.As the periodic table took shape, scientists noted certain properties and trends.  For example, Rayleigh and Ramsay observed that some elements are unreactive and gave them the name noble gases.  But it was not until Niels Bohr described his model of the atom that scientists understood why noble gases are stable.Another important trend was discovered by Linus Pauling.  He was the first to identify electronegativity as a way to describe bonds that are neither completely ionic nor completely covalent.  Pauling assigned fluorine the highest electronegativity value of 4.0 because of its strong tendency to attract electrons when bonded to other atoms.  All other atoms were assigned values relative to fluorine.  This became known as the Pauling electronegativity scale.Scientists identified other trends based on x-ray crystallography and reactivity studies.  Figure 1 shows the first ionization energy of the elements, and Figure 2 shows electron affinity.Figure 1  First ionization energy of elementsFigure 2  Electron affinity of several elements (larger negative values indicate greater electron affinity) Question 35According to the information in the passage, in general, adding electrons to nonmetals is:A.not possible for most nonmetals.B.energetically similar to adding electrons to metals.C.easier than adding electrons to metals.D.more difficult than adding electrons to metals.

which of the following is not correct about the discovery of atoms?1 pointplum pudding model is given by JJ Thomsonrutherford is also known as the father of nuclear physicsneutron is discovered by Neil bohrrutherford failed to explain why electron is not losing energy and falling into the nucleus