Chem Midterm Exam

This set of flashcards includes key concepts and definitions related to chemistry, focusing on chemical changes, measurements, atomic structure, and periodic trends.

What do chemical changes affect?

Physical and chemical properties.

What type of measurement includes the correct number of significant figures?

A precise measurement.

How is 5,800,000,000 cm expressed in scientific notation?

5.8 x 10^9 cm.

What is the result of multiplying (5.2 x 10^6) by (5.0 x 10^3)?

2.6 x 10^10.

How is accuracy judged?

By how close a value is to the true value.

What is the scientific notation for 0.0000043 g?

4.3 x 10^-6 g.

What is the speed of light in conventional notation?

300,000,000 m/s.

What is 78,900,000,000 in scientific notation?

7.89 x 10^10.

How does a phosphorus atom become a phosphide ion (P3-)?

It increases in radius.

What happens to a cadmium atom when it becomes a cadmium ion (Cd²+)?

It loses two electrons and its radius decreases.

What happens to the radius of an atom when it becomes a positive ion?

The radius decreases.

Which corner of the Periodic Table has the most nonmetallic properties?

Upper right.

Which element in Period 3 has the largest atomic radius?

Na (Sodium).

As atomic number increases in Group 2, what happens to atomic radius?

It increases due to an increase in occupied principal energy levels.

What trend occurs when moving from atomic number 3 to 9 on the Periodic Table?

Atomic radius decreases as nuclear charge increases.

What is the characteristic of elements in Period 3 from left to right?

Metallic character decreases and electronegativity increases.

What type of atoms are found on the stair step line in the Periodic Table?

Metalloids.

What is the charge of an atom determined by?

The number of protons and electrons.

How many neutrons does an iron atom with an atomic mass of 56 and atomic number of 26 have?

30 neutrons.

What does an element's atomic number equal?

The number of protons.

What differentiates isotopes of an element?

Different numbers of neutrons.

What is the mass number of an element with 19 protons and 20 neutrons?

39.

What does oxygen's atomic number of 8 indicate?

Eight protons in its nucleus.

What is the definition of average atomic mass?

A weighted average based on the abundance of each isotope.

What are atoms that gain or lose electrons called?

Ions.

What is the scientific notation for 0.0005?

5 x 10^-4.

How do you express 5501 in scientific notation?

5.501 x 10^3.

What is 98700000 written in scientific notation?

9.87 x 10^7.

What is the scientific notation for 15000000?

1.5 x 10^7.

What is the scientific notation for 0.000000045?

4.5 x 10^-8.

How do you write 0.000000980 in scientific notation?

9.8 x 10^-7.

How do you multiply (3.4 x 10^2) by (2 x 10^1)?

6.8 x 10^3.

What is 20,000 X 1700 in scientific notation?

3.4 x 10^7.

What is the product of 25 X 7000 in scientific notation?

1.75 x 10^5.

How do you multiply (8 x 10^-5) by (4.2 x 10^-3)?

3.36 x 10^-7.

What is the answer for (5.23 x 10^1) X (2.1 x 10^2)?

1.10 x 10^4.

What is the periodic trend for nonmetals?

They are located towards the upper right of the Periodic Table.

What is the periodic trend for atomic radius across a period?

Atomic radius decreases.

What elements typically have the largest atomic radius in a given period?

The alkali metals.

What happens to the atomic radius as you move down a group in the Periodic Table?

It increases.

What is the overall charge of the nucleus of an atom?

Positive.

What is an element that has both positive and negative charges called?

Ion.

What is the chemical formula of a compound formed by sodium and oxygen?

Na2O.

What can you infer about an ionic compound's melting point?

Generally has a high melting point.

Substances that conduct electricity when dissolved in water are classified as?

Ionic compounds.

Which of the following determines the charge of an ion formed from an atom?

The number of outer shell electrons.

What do you call an ion formed by losing electrons?

Cation.

What does a covalent bond involve?

The sharing of electrons.

Which type of bond is typically formed between metals and nonmetals?

Ionic bond.

What is the formula for potassium chloride?

KCl.

What occurs during the formation of covalent bonds?

Electrons are shared between atoms.

In chemical bonding, what do we call atoms that gain electrons?

Anions.

Which type of bond is likely formed between two nonmetals?

Covalent bond.

What occurs if a covalent bond is broken?

The atoms may become separate or form new bonds.

What is the term for the simplest whole number ratio of atoms in a compound?

Empirical formula.

What describes the ratio of atoms in covalent compounds?

Molecular formula.

What kind of compound is formed when sodium reacts with chlorine?

Ionic compound.

How can you tell if a substance is ionic?

It conducts electricity when melted.

What happens during a chemical change?

New substances are formed.

What is the term for a positively charged ion?

Cation.

What is the characteristic behavior of metals in reactions?

They tend to lose electrons.

What makes up the nucleus of an atom?

Protons and neutrons.

What determines the overall charge of an atom?

The difference between protons and electrons.

What is the term for atoms with the same atomic number but different masses?

Isotopes.

What aspects do significant figures count?

Both the precision and the accuracy of measurements.

Which of the following has a full outer shell?

Noble gases.

What is the main feature of transition metals?

They can form multiple oxidation states.

What happens to ionic compounds when melted?

They conduct electricity.

What is the characteristic of a metallic bond?

Electron sharing among many atoms.

What type of property is reactivity?

Chemical property.

What does a balanced chemical equation represent?

The law of conservation of mass.

How do you know if a reaction is a synthesis reaction?

Two or more reactants combine to form one product.

What does the term electronegativity refer to?

An atom's ability to attract electrons.

What is the trend of electronegativity across a period?

It increases.

What occurs in a decomposition reaction?

A single compound breaks down into two or more simpler substances.

What type of reaction occurs when an acid reacts with a base?

Neutralization reaction.

What is produced in a complete combustion reaction?

Carbon dioxide and water.

What happens to energy in a chemical reaction?

It is either absorbed or released.

What is the primary distinguishing feature of acids?

They produce hydrogen ions in solution.

What kind of reaction is an oxidation-reduction reaction?

Transfer of electrons.

What happens when an electron is removed from an atom?

The atom becomes a positive ion.

What is the molecular geometry of a water molecule?

Bent.

What do acids and bases create when mixed?

Salt and water.

What is the role of catalysts in chemical reactions?

They speed up the reaction without being consumed.

What is the principal reason for the periodic table's layout?

Increasing atomic number.

Which element is in group 2 and period 2 of the periodic table?

Beryllium.

What is formed during a chemical reaction?

Products.

How do elements within the same group of the periodic table compare?

They have similar chemical properties.

What happens to the atomic number of elements as you move across a period?

It increases.

What is determined by the number of valence electrons?

An element's reactivity.

Which of the following describes a polar bond?

Unequal sharing of electrons.

What does a dipole moment indicate?

Polar molecules.

In a ionic bond, what is transferred?

Electrons.

What are a set of chemical symbols and numbers that show the ratio of atoms in a compound?

Chemical formula.

What type of substance can be separated into its components by physical means?

Mixture.

What process involves changing solid into gas?

Sublimation.

What is the significance of a catalyst?

It lowers the activation energy of a reaction.

What is one way to tell a chemical change has occurred?

Change in color.

What type of gas is typically produced in a reaction that produces bubbles?

Gas.

What does a balanced equation ensure?

Conservation of mass.