Science chapter 1-7 test

Describe the displacement method for measuring the volume of an object.

Add water to a measuring container such as a graduated cylinder. Record the volume of the water. Place the object in the water in the graduated cylinder. Measure the volume of the water with the object in it. Subtract the first volume from the second volume. The difference represents the volume of the object.

What are alkali metals? What is one example?

Alkali metals are the elements in group 1 which have 1 valence electron. They are highly reactive. They are only found in nature combined with other elements. They are soft enough to be cut with a knife and have a low density. All are solids at room temperature. Examples include, Lithium, Sodium, Potassium, Rubidium, Cesium, and Francium.

Identify an alkaline Earth metal. How reactive is it?

Alkaline earth metals are the elements from group 2 and contain 2 valence electrons. They are very reactive, though not as much so as the Alkali metals. They are always found combined with other elements. They are silvery gray in color and harder and denser then alkali metals. They are all solids at room temperature. Examples include Beryllium, Magnesium, Calcium, Strontium, Barium, and Radium.

Define matter.

Define matter.

State why halogens are highly reactive.

Halogens are highly reactive because they are lacking only a single valence electron. They want badly to fill their outer shell so will react readily with other elements to fill that gap. They react in particular to the Alkali metals which have one "extra" valence electron.

Both hydrogen (H) and helium (He) are gaseous nonmetals. Why are they placed on opposite sides of the periodic table?

Hydrogen is a highly reactive element, having 1 valence electron, making it an alkali metal. Helium however is an element that is not reactive since its outermost shell is full, making it a noble gas.

How does mass differ from weight?

Mass is the amount of matter in a substance or object, while weight is the measure of the force of gravity pulling on an object.

In which groups of the periodic table would you find metalloids?

Metalloids occur in groups 13-16. They appear around the stair step pattern of transition metals.

Describe noble gases.

Noble gases do not react with other elements. They are all nonmetals, and exist as colorless, odorless gases. Their outer energy levels are full of valence electrons, so they do not want to react or combine with other elements.

Assume you have a sample of an unknown element. At room temperature, it is a soft solid. You cut a small piece from the sample with a knife and drop the piece into a container of water. It bursts into flames. Which group of the periodic table does the unknown element belong in?

This element has to be an Alkali metal, since elements in that group are characterized as being reactive, and a solid soft enough to be cut with a knife.