Expert Answers


The ___________________ is the variable that changes in response to the manipulated variable.

From left to right across a period in the periodic table, elements become less  and more ______________ in their properties.

Francium has 36 isotopes, but only francium-223 occurs in nature. Francium-223 spontaneously emits particles and energy, so francium-223 is a(an) _____________ of francium.

Cooking requires continuous addition of energy to the chemical reactions that are taking place. The chemical reactions involved in cooking can be described as __________________.

The ________________ theory of matter states that all particles of matter are in constant motion.

A student balanced the chemical equation Mg + O2 → MgO by writing Mg + O2 → MgO2. Was the equation balanced correctly? Explain your answer. If the equation was not balanced correctly, write the correctly balanced equation.

On the periodic table, there are two numbers in the block for the element potassium, K: 19 and 39.098. What are these two numbers, and what do they represent?

Element X has five valence electrons, element Y has one valence electron, and element Z has five valence electrons. Which two of these elements are most likely to have similar properties? Explain your answer.

In Rutherford’s gold foil experiment, some of the _______________ aimed at gold atoms bounced back, suggesting that a solid mass was at the center of the atom.

At sea level, water ______________ at 100°C.

John Dalton concluded that all the atoms of a single ______________ have the same mass.

What naturally occurring radioisotope is used as the fuel for a nuclear reactor?

In an experiment, if doubling the manipulated variable results in a doubling of the responding variable, the relationship between the variables is a(an) ______________.

You are given the melting points of three unknown substances and are asked to predict which one is an ionic compound. You would select the compound with the ________________ melting point.

A flight simulator that helps astronauts prepare for a shuttle launch is an example of a(an) __________________.

What are three common clues that a chemical change has occurred?

A cake rises as it bakes because a chemical change causes ___________________ to be produced.

In the symbol   He, the superscript 4 is the _________________ for helium, and the subscript 2 is the ___________________ for helium.

Charles’s law can be written as   . Explain what T1 and T2 represent.

How do you know that magnesium is the more metallic element in the compound magnesium oxide, MgO?