The Periodic TableRegents Review

2. The first ionization energy of an element is 736 kJ per mole of atoms. How many valence electrons does an atom of this element in the ground state have? A) 1B) 2C) 3D) 4

• Correct Answer: Option B - 2

• The element having the first ionization energy of, 736 kJ/mol is Magnesium.

3. Which element in Group 15 has the strongest metallic character? A) AsB) PC) ND) Bi

• Correct Answer: Option D - Bi• From left to right across the period, metallic character

decreases. But it increases going down a group (last element in a group will have the most metallic character). Bi is the last element in group 15 so it is the most metallic. Order of group 15 elements in descending rate of metallic character is: Bi(Bismuth), Sb(Antimony), As(Arsenic), P(Phosphorus) and N(Nitrogen).

4. Which compound forms a colored aqueous solution? A) CaCl22

B) CrCl3

C) NaOHD) KBr

• Correct Answer: Option B - CrCl3

• Colored aqueous solutions are a characteristic of transition compounds. The only transition compound in the above choices is CrCl3. Cr is a transition element.

5. Which element has the highest first ionization energy? A) SodiumB) PhosphorusC) AluminumD) Calcium

• Correct Answer: Option B: Phosphorus• The energy needed to remove one or more electrons from a

neutral atom to form a positively charged ion is a physical property that influences the chemical behavior of the atom. By definition, the first ionization energy of an element is the energy needed to remove the outermost or highest energy, electron from a neutral atom in the gas phase

6. Which of the following elements has the smallest atomic radius?A) NickelB) CobaltC) PotassiumD) Calcium

• Correct Answer: Option A - Nickel• Atomic radius is called the width of an atom, but it is not a precisely

defined physical quantity, nor is it constant in all circumstances. Atomic Radius gets greater down the periodic table and gets smaller to the right in the periodic table. Going from left to right across the periodic table, the number of protons increases. The more they increase, the more they pull and attract the outer electrons from the outermost electron shell, making the atomic radius smaller.

7. Which set of elements contains a metalloid? A) Li, Mg, Ca, KrB) Ba, Ag, Sn, XeC) K, Mn, As, ArD) Fr, F, O, Rn

• Correct Answer: Option C - K, Mn, As, Ar• The metalloids are elements which have intermediate

properties and cannot be classified as either metals or nonmetals. They are also referred to as semimetals.

• In the Periodic Table, the location of the stepped line divides metals and nonmetals. Elements next to the left or right of this line are metalloids. This clearly lists Aresenic as a metalloid which is a part of option C.

8. An atom of which of the following elements has the greatest ability to attract electrons?A) ChlorineB) SiliconC) SulfurD) Nitrogen

• Correct Answer: Option A - Chlorine • Electronegativity is a chemical property that describes the ability

of an atom to attract electrons towards itself in a covalent bond.

10. Atoms of elements in a group on the Periodic Table have similar chemical properties. This similarity is most closely related which characteristic of the atoms? A) Number of principal energy levelsB) Atomic numbersC) Number of valence electronsD) Atomic masses

• Correct Answer: Option C - Number of valence electrons• Most of the time elements in the same group have the same

number of valence electrons. Valence electrons are involved in bonding and this effects how elements react and determines their chemical properties.

11. Most of the groups in the Periodic Table of the elements contain: A) Nonmetals onlyB) Nonmetals and metalsC) Metals onlyD) Metals and metalloids

• Correct Answer: Option C - Metals only• One reason the periodic table of the elements is so useful is because it

is a means of arranging elements according to their similar properties. There are multiple ways of grouping the elements, but they are commonly divided into metals, semimetals, and nonmetals. Most elements are metals. There are so many metals, they are divided into groups: alkali metals, alkaline earth metals, and transition metals. The transition metals can be divided into smaller groups, such as the lanthanides and actinides.

12. In Period 2 of the Periodic Table, which Group contains the element with the highest first ionization energy?

A) Alkali metalsB) Noble gasesC) Alkaline earth metalsD) Halogens

• Correct Answer: Option B - Noble gases

13. The elements in Period 3 all contain the same number of A) ProtonsB) Valence electronsC) Occupied principal energy levelsD) Neutrons

• Correct Answer: Option C - Occupied principal energy levels• A period 3 element is one of the chemical elements in the third

row (or period) of the periodic table of the chemical elements. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behavior of the elements as their atomic number increases: a new row is begun when chemical behavior begins to repeat, meaning that elements with similar behavior fall into the same vertical columns

14. Compared to atoms of metals, atoms of nonmetals generally A) Have lower first ionization energiesB) Conduct electricity more readilyC) Have higher electronegativitiesD) Lose electrons more readily

• Correct Answer: Option C - Have higher electronegativities• Electronegativity is a chemical property that describes the

ability of an atom to attract electrons towards itself in a covalent bond.

• Atoms of metals have higher first ionization energies, conduct electricity more readily and also lose electrons more readily

16. When a metal atom combines with a nonmetal atom, the nonmetal atom will A) Lose electrons and decrease in sizeB) Gain electrons and increase in sizeC) Lose electrons and increase in sizeD) Gain electrons and decrease in size

• Correct Answer Number: B - Gain electrons and increase in size• Metals are Electropositive Elements. Metals are very reactive. Metals

tend to loose electrons easily and form positively charged ions; therefore metals are called electropositive elements. Sodium metal forms sodium ions Na+, Mg forms positively charged Magnesium ions Mg2+ and aluminium forms aluminium ions Al3+. The electropositive nature allows metals to form compounds with other elements easily

17. Which halogens are gases at standard temperature and pressure? A) Iodine and fluorineB) Chlorine and bromineC) Chlorine and fluorineD) Iodine and bromine

• Correct Answer: Option C - Chlorine and fluorine

18. As the elements of Group 17 are considered in order of increasing atomic number, there is an increase in: A) First ionization energyB) Number of electrons in the first shellC) ElectronegativityD) Atomic radius

• Correct Answer: Option D - Atomic radius

19. At STP, which substance is the best conductor of electricity? A) SilverB) NitrogenC) SulfurD) Neon

• Correct Answer: Option A - Silver

20. Which two characteristics are associated with metals? A) Low first ionization energy and low electronegativityB) High first ionization energy and low electronegativityC) High first ionization energy and high electronegativityD) Low first ionization energy and high electronegativity

• Correct Answer: Option A - Low first ionization energy and low electronegativity

23. Which group on the Periodic Table contains elements that react with oxygen to form compounds with the general formula X2O?

A) Group 14B) Group 1C) Group 2D) Group 18

• Correct Answer: Option B - Group 1• Elements of group 1 are Hydrogen (H), Lithium (Li), Sodium (Na),

Potassium (K), Rubidium (Rb), Cesium (Cs), Francium (Fr). All these elements have 1 valence electron available for reaction. Oxygen has 6 valence electrons which requires 2 additional electrons for completing the last subshell. Hence, oxygen reacts with 2 atoms of each of the group 1 elements to form a compound X2O.

24. In the ground state, each atom of an element has two valence electrons. This element has lower first ionization energy than calcium. Where is this element located on the Periodic Table? A) Group 1, Period 4B) Group 2, Period 3C) Group 3, Period 4D) Group 2, Period 5

• Correct Answer: Option D - Group 2, Period 5• Valence electrons in each of the group in a periodic table is related to the

group to which an element belongs to; i.e. elements in group 1 have 1 valence electron, elements in group 2 have 2 valence electrons, etc.

• Hence, the element mentioned above has to be in group 2.• Also the first ionization energy reduces as you go down a group. Calcium lies

in period 4. Hence, the element being referred in the question is in period 5.• The element referred to is Strontium (Sr).

26. As the atoms of the elements in Group 1 of the Periodic Table are considered from top to bottom, the number of valence electrons in the atoms of each successive element A) IncreasesB) DecreasesC) Remains the sameD) Reduces to zero

• Correct Answer: Option C - Remains the same• The valence electrons are the electrons in the last shell or energy level of an atom.

They do show a repeating or periodic pattern. The valence electrons increase in number as you go across a period. Then when you start the new period, the number drops back down to one and starts increasing again.

• For example, when you go across the table from carbon to nitrogen to oxygen, the number of valence electrons increases from 4 to 5 to 6. As we go from fluorine to neon to sodium, the number of valence electrons increases from 7 to 8 and then drops down to 1 when we start the new period with sodium. Within a group--starting with carbon and going down to silicon and germanium--the number of valence electrons stays the same.

28. How do the atomic radius and metallic properties of sodium compare to the atomic radius and metallic properties of phosphorus?

A) Sodium has a larger atomic radius and is more metallic.B) Sodium has a larger atomic radius and is less metallic.C) Sodium has a smaller atomic radius and is more metallic.D) Sodium has a smaller atomic radius and is less metallic.

• Correct Answer: Option A- Sodium has a larger atomic radius and is more metallic.

30. What is the total charge of the nucleus of a carbon atom? A) -6B) +6C) 0D) +10

• Correct Answer: Option B - +6

• Every carbon atom contains six positively charged particles called protons in its nucleus and six or more neutral particles called neutrons. The carbon atom's nucleus is surrounded by six negatively charged electrons

• Same Group so same number of valance electrons thus they have similar properties