Chpt. 11 HW Reading Check

What element has the lightest atoms? a) Hydrogen b) Helium c) Positronium d) Lithium

a) Hydrogen

Consider the following atoms: A. Magnesium. B. Niobium. C. Dubnium. D. Tantalum. Part A Rank from most to least. To rank items as equivalent, overlap them. Part B Consult the periodic table and rank these atoms, from most to least, by their number of electrons. Part C Consult the periodic table and rank these atoms, from most to least, by their number of protons.

Part A A, D, B, C (atomic mass) Db-105(262) Ta-73(180.948) Nb-41(92.906) Mg-12(24.305) Part B C, D, B, A Db-105, Ta-73, Nb-41, Mg-12 Part C C, D, B, A

What causes dust particles and tiny grains of soot to move with Brownian motion? What causes dust particles and tiny grains of soot to move with Brownian motion? a) Collisions with invisible molecules b) The element fire c) Flowing currents d) Collisions with transparent microorganisms

a) Collisions with invisible molecules

Since atoms are mostly empty space, why don't we fall through a floor we stand on? a) Electrons in one atom repel the electrons in another. b) Positively charged nuclei attract electrons from neighboring atoms, so they always collide. c) The atoms are always in motion, so they collide often. d) The positively charged nuclei repel each other.

a) Electrons in one atom repel the electrons in another.

Where in the atom is most of its mass concentrated? What is this mass composed of? a) In the nucleus as protons and neutrons b) In the electron cloud c) In a cloud of nucleons surrounding the nucleus d) In the nucleus as electrons

a) In the nucleus as protons and neutrons

Dark matter is considered to be __________. a) plentiful in the universe b) a form of dark energy c) at the center of all atomic nuclei d) a local phenomenon

a) plentiful in the universe

How does one isotope differ from another? a) It has a different electric charge. b) It has a different number of neutrons. c) It has a different number of electrons. d) It has a different number of protons.

b) It has a different number of neutrons.

How are most of the elements with nuclei heavier than those of hydrogen and helium formed? a) Nuclear fission in supernovas b) Nuclear fusion in stars

b) Nuclear fusion in stars

Where did the heaviest elements originate? a) Nuclear fusion in stars b) Nuclear fusion in supernovae

b) Nuclear fusion in supernovae

What is the evidence that dark matter exists? a) When dark matter clouds collide, they emit light. b) Dark matter blocks distant light and can be seen as dark clouds in space. c) Gravitational forces within galaxies are too great to be accounted for with ordinary matter. d) When dark matter falls into a black hole, it emits light.

c) Gravitational forces within galaxies are too great to be accounted for with ordinary matter.

What does the atomic number of an element tell you about the element? a) The number of electrons in its nucleus b) The number of neutrons in its nucleus c) The number of protons in its nucleus d) The number of nucleons in its nucleus

c) The number of protons in its nucleus

What occurs when a proton and an antiproton meet? a) They gravitationally repel each other. b) They electrically repel each other. c) They annihilate each other. d) They do not interact in any way.

c) They annihilate each other.

How do matter and antimatter differ? a) Antimatter has negative weight. b) Matter gravitationally attracts matter and repels antimatter. c) When matter and antimatter meet, they annihilate in a flash of energy. d) Matter emits light, whereas antimatter absorbs it.

c) When matter and antimatter meet, they annihilate in a flash of energy.

What is meant by the term nucleon? a) A quark b) Antimatter c) An electron d) A proton or neutron

d) A proton or neutron

What is a compound? Cite two examples. a) Atoms pressed together without bonding: air and salt and sand b) Atoms of different elements with bonds between them: NaCl and H2 c) The same types of atoms bonded together: H2 and N2 d) Atoms of different elements with bonds between them: NaCl and H2O

d) Atoms of different elements with bonds between them: NaCl and H2O

What is the most abundant element in the known universe? a) Iron b) Helium c) Carbon d) Hydrogen

d) Hydrogen

How does the electric charge of a proton compare with the electric charge of an electron? a) It is about 2000 times larger. b) It is about 2000 times larger and opposite in sign. c) It is equal. d) It is equal and opposite.

d) It is equal and opposite.

The periodic table of the elements is a list of __________. a) ions b) molecules c) isotopes d) atoms

d) atoms

The charge in the nucleus of an antimatter hydrogen atoms is __________. a) neutral, no charge b) positive c) exotically different than positives and negatives d) negative

d) negative

The number of atoms in a common water molecule is __________. a) four b) two c) one d) three

d) three

An important feature of atoms is that they __________. a) are actually tiny solar systems b) have wave properties c) can barely be seen with the naked eye d) make up electric beams

b) have wave properties