Benchmark for Chemistry-1

You are excited to learn that you have been chosen to be your chemistry teacher lab assistant! She asked you to put away the element samples she used earlier today. You are doing fine until you reach sample #4. This solid sample is not labeled! Using the process of elimination you know the unknown element must be aluminum, calcium, sodium, or sulfur. What element is it? To help determine the identity of the element, the following data were obtained for unknown sample #4, called X. Sample mass: 27.5 g Appearance: Silver gray colored solid, shiny surface when scratched Conductivity: yes Oxide formula: XO Reaction with water: Vigorous reaction produced flammable gas and white precipitate. The pH of the water increased from 7 to 10.

• Al

• Ca

• Na

• S

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

The periodic table of the elements organizes elements according to their properties. A section of the periodic table is shown. Select the three elements from the choices below that are most similar in chemical behavior.

• Be

• Ca

• K

• Ra

• Sc

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

Which among the following shows the elements correctly ordered by increasing atomic radii?

• Mg < K < Na < Rb

• Mg < Na < Rb < K

• Mg < Na < K < Rb

• Rb < Na < K < Mg

Tags

NGSS.HS-PS1-1

Group 17 elements are called halogens and have 7 valence electrons. The table shows the atomic radius, in picometers (pm), of some Group 17 elements. Element Atomic Radius (pm) Fluorine 135 Chlorine 175 Bromine 183 Iodine 198 Which element has the highest ionization energy?

• Fluorine

• Chlorine

• Bromine

• Iodine

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

Carbon and silicon are located in group 14 (4A) on the periodic table. How are carbon and silicon different?

• Carbon has an atomic mass of 6, and silicon has an atomic mass of 14.

• Carbon has 2 shells of electrons, and silicon has 3 shells of electrons.

• Carbon has 12 electrons, and silicon has 28 electrons.

• Carbon has 14 protons, and silicon has 28 protons.

Tags

NGSS.HS-PS1-1

According to VSEPR theory, molecules of which of these compounds have a trigonal planar geometry?

• acetylene, C2H2

• carbon dioxide, CO2

• carbon tetrachloride, CCl4

• formaldehyde, H2CO

A Lewis dot diagram shows the shape of a water molecule and the locations of the electrons. Select all of the terms below that describe a water molecule as illustrated by the dot structure.

• bent

• linear

• polar

• nonpolar

• tetrahedral

A student found a video on-line that showed the reaction of metals with oxygen. The formulas reported for the metal oxides were reported as NaO, MgO, AlO, and SiO. As a knowledgeable chemistry student you noticed that only one of these formulas is correct. Which of the following formulas for a metal oxide is correct?

• MgO

• NaO

• AlO

• SiO

Tags

NGSS.HS-PS1-1

Identify the cation and anion: Ca 2+ is an anion.

• True

• False

Identify the cation and anion: O2- is an anion.

• True

• False