Atomic Structure and Periodic Properties Quiz

The basic building blocks of the substances are atoms.

 a. Water is composed of hydrogen (H) and oxygen (O) atoms.
 b. Chalk is primarily composed of calcium (Ca), carbon (C) and oxygen (O) atoms.
 c. Sugar is composed of carbon (C), hydrogen (H) and oxygen (O) atoms.
 d.  Table salt is composed of sodium (Na) and chlorine (Cl) atoms.

The basic building blocks of these substances are different. Each substance is made up of unique combinations of atoms.

The different properties of materials arise from differences in their atomic composition and how their atoms are arranged.

Our understanding of the structure of matter has evolved over time through a combination of observation, experimentation, and theoretical development.

<p>Early developments leading to the modern concept of the atom include the ideas of the Greek philosopher Democritus who proposed the existence of indivisible particles called atoms. These ideas paved the way for further exploration and understanding of the atom's composition.</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>Dalton's atomic theory proposes five key postulates:</p> <ol> <li>All matter is composed of atoms, which are indivisible and indestructible particles.</li> <li>All atoms of a given element are identical in mass and properties.</li> <li>Atoms of different elements have different masses and properties.</li> <li>Compounds are formed by the combination of two or more different kinds of atoms in a definite ratio by mass.</li> <li>Chemical reactions involve the rearrangement of atoms. Atoms are neither created nor destroyed in chemical reactions.</li> </ol> Signup and view all the answers

<p>Scientific ideas develop through a process of building upon prior knowledge and observations. Previous scientific findings provide a foundation for further inquiry and exploration, leading to refinements and new discoveries.</p> Signup and view all the answers

<p>The law that Dalton formulated based on the law of conservation of mass and the law of definite proportions is the Law of Multiple Proportions. The law states that when two elements form more than one compound, the masses of one element that combine with a fixed mass of the other element are in ratios of small whole numbers.</p> Signup and view all the answers

<p>This does not indicate that mass is created or destroyed. When wood burns, it reacts with oxygen in the air. The resulting products, including ash, carbon dioxide, and water vapor, have a combined mass equal to the initial mass of the wood and oxygen. The mass simply changes form, not disappears.</p> Signup and view all the answers

<p>The total mass of the products in a closed container would be equal to the initial combined mass of the wood and oxygen. Since the container prevents any escape of gases, the entire mass of reactants would be transformed into products.</p> Signup and view all the answers

<p>When sugar is burned, the hydrogen and oxygen atoms combine with oxygen from the air to form water vapor (H2O) and carbon dioxide (CO2). These gases are released into the atmosphere, leaving behind the black carbon residue.</p> Signup and view all the answers

<p>a. Mass of hydrogen in 18.0 g water = 0.112 × 18.0 g = 2.02 g Mass of oxygen in 18.0 g water = 0.888 × 18.0 g = 15.98 g</p> <p>b. Mass of hydrogen in 1.00 g water = 0.112 × 1.00 g = 0.112 g Mass of oxygen in 1.0 g water = 0.888 × 1.0 g = 0.888 g</p> Signup and view all the answers

<p>The ratios of nitrogen masses combining with 1 gram of oxygen in each pair of compounds should be small whole numbers to support the law of multiple proportions. The ratios are:</p> <p>A/C = 1.750 / 0.4375 = 4 B/C = 0.8750 / 0.4375 = 2</p> <p>These results demonstrate small whole number ratios, supporting the Law of Multiple Proportions.</p> Signup and view all the answers

<p>The postulates of Dalton's atomic theory that are still significant include:</p> <ol> <li>All matter is composed of atoms.</li> <li>Atoms of different elements have different masses and properties.</li> <li>Compounds are formed by the combination of two or more different kinds of atoms.</li> </ol> Signup and view all the answers

<p>The atomic theory explains this consistency because water is always composed of the same elements in the same proportions (two hydrogen atoms and one oxygen atom). Regardless of the origin of the water, the ratio of hydrogen to oxygen will remain constant, as dictated by the atomic theory.</p> Signup and view all the answers

<p>One of Dalton's postulates, that atoms are indivisible and indestructible, was later found to be inconsistent with the discovery of subatomic particles like electrons, protons, and neutrons. While these inconsistencies show that Dalton's theory was not perfect, his work was revolutionary, laying the foundation for our modern understanding of the atom.</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>Dalton's atomic theory had several limitations, primarily:</p> <ol> <li>Atoms are not indivisible and indestructible. They are composed of subatomic particles like electrons, protons, and neutrons.</li> <li>Atoms of the same element are not necessarily identical in mass. The existence of isotopes, atoms of the same element with different numbers of neutrons, challenges this postulate.</li> <li>Dalton's theory does not account for the behavior of atoms in the formation of molecules and the role of electrons in chemical bonding.</li> </ol> Signup and view all the answers

<p>The modern atomic theory is based on the following postulates:</p> <ol> <li>All matter is composed of tiny, indivisible particles called atoms.</li> <li>Atoms of a given element are chemically identical but differ from atoms of other elements in mass and properties.</li> <li>Atoms of different elements can combine in simple, whole-number ratios to form chemical compounds.</li> <li>Chemical reactions involve the rearrangement, combination, or separation of atoms but do not involve the creation or destruction of atoms.</li> <li>Atoms are composed of subatomic particles: electrons (negatively charged), protons (positively charged), and neutrons (no charge).</li> </ol> Signup and view all the answers

<p>The three fundamental laws of chemistry are:</p> <ol> <li>The law of Conservation of Mass: Mass is neither created nor destroyed in ordinary chemical reactions.</li> <li>The law of Definite Proportions: A given compound always contains the same elements in the same proportion by mass.</li> <li>The law of Multiple Proportions: When two elements combine to form more than one compound, the masses of one element that combine with a fixed mass of the other element are in ratios of small whole numbers.</li> </ol> Signup and view all the answers

<p>The modern atomic theory explains the fundamental laws of chemistry by emphasizing the conservation of atoms during chemical reactions. The law of conservation of mass is explained by the idea that atoms are not created or destroyed in chemical reactions, but are simply rearranged. The law of definite proportions is explained by the idea that compounds are formed from specific combinations of atoms in fixed ratios. The law of multiple proportions is explained by the concept that atoms of different elements can combine in different ratios to form different compounds, with those ratios being simple whole numbers.</p> Signup and view all the answers

<p>Cathode rays, discovered by J.J. Thomson, exhibit the following properties:</p> <ol> <li>They travel in straight lines from the cathode to the anode.</li> <li>They are deflected by magnetic fields and electric fields, indicating they carry a negative charge</li> <li>Their properties are independent of the material used for the cathode, which suggests that they are a fundamental constituent of all matter.</li> <li>They produce greenish light when they interact with glass.</li> </ol> Signup and view all the answers

<p>X-rays are used to see whether bones are broken or not. X-rays have higher energies than visible light and can penetrate human tissues. When they interact with bones, they are partially absorbed, revealing structural information.</p> Signup and view all the answers

<p>Radioactivity contradicts Dalton's idea of atoms being indivisible. Radioactive decay demonstrates that atoms can break down into smaller particles, challenging the notion of atoms as fundamental, indivisible units.</p> Signup and view all the answers

<p>All of the above</p> Signup and view all the answers

<p>Most of the α-particles passed through the gold foil undeflected because atoms are mostly empty space. The α-particles were small and positively charged, and they interacted primarily with the electrons, which are much lighter, and the nucleus, which is very small.</p> Signup and view all the answers

<p>A small fraction of the α-particles showed slight deflection because they encountered the positive charge of the nucleus. As positively charged α-particles approached the positively charged nucleus, they experienced electrostatic repulsion, causing them to deviate from their original paths.</p> Signup and view all the answers

<p>Not all α-particles bounced back at an angle of 180° because the nucleus is very small compared to the size of the atom. If the α-particles were to pass through the exact center, they would experience a direct head-on collision and bounce back. However, most particles passed close to the nucleus, experiencing only a partial deflection.</p> Signup and view all the answers

<p>Based on the findings of Rutherford's experiment, we can conclude that</p> <ol> <li>Atoms are mostly empty space, as the majority of α-particles passed through the gold foil undeflected.</li> <li>Atoms contain a dense, positively charged nucleus, as a small fraction of α-particles experienced significant deflection.</li> <li>The nucleus occupies a very small fraction of the atom's total volume.</li> </ol> Signup and view all the answers

<p>Rutherford's experiment overturned Thomson's plum-pudding model because it demonstrated that the positive charge of an atom is concentrated in a small, dense nucleus, rather than being uniformly distributed throughout the atom. This contradicted Thomson's model, which assumed a diffuse positive charge with electrons embedded within it, where electrons could easily scatter α-particles.</p> Signup and view all the answers

<p>A radioactive element is undergoing radioactive decay, which involves the emission of particles and/or radiation from the nuclei of unstable atoms. This emission results in the transformation of the radioactive element into a different element, with a corresponding decrease in mass.</p> Signup and view all the answers

<p>The experimental basis for believing that the nucleus occupies a very small fraction of the volume of the atom comes from Rutherford's alpha-scattering experiment. In this experiment, the majority of α-particles passed straight through the gold foil, indicating that the atoms were largely empty space. Only a small fraction of particles were deflected, suggesting that the positive charge of the atom was concentrated in a small, dense nucleus.</p> Signup and view all the answers