SOL Review: Atomic Structure and Periodic Trends

A neutral atom of calcium has 20 electrons. Calcium forms a 2+ ion. How many electrons does a calcium ion have?

A Ca2+'ion has the same nucleus as the neutral atom, which has 20 protons and 20 neutrons. The neutral atom also has 20 electrons, but to form the 2+ ion, it needs to lose 2 of these, giving just 18 electrons.

Element 1 - 20 protons, 20 neutrons, 20 electrons. Element 2 - 40 protons, 40 neutrons, 40 electrons. Element 3 - 20 protons, 10 neutrons, 10 electrons Element 4 - 20 protons, 20 neutrons, 40 electrons. Which represents an atom of calcium?

According to the Periodic Table of Elements, calcium's atomic number is 20. This means that every atom of calcium contains 20 protons. If an atom contains some other number of protons, it isn't an atom of calcium. Protons carry a positive charge, so the nucleus of an atom of calcium carries a charge of +20. Electrons carry a negative charge. If the net charge on an calcium atom is zero, then the atom must have 20 negatively charged electrons surrounding the nucleus: Net Charge=(Number of Positive Charges)−(Number of Negative Charges)Net Charge=(Number of Positive Charges)-(Number of Negative Charges) 0=20−Number of Electrons0=20-Number of Electrons 0−20=-(Number of Electrons)0-20=-(Number of Electrons) -20=-(Number of Electrons)-20=-(Number of Electrons) 20=Number of Electrons20=Number of Electrons According to the Periodic Table of Elements, calcium's atomic mass is about 40. This means that an average atom of calcium contains 40 particles in its nucleus. The nucleus is made from protons and neutrons. Since every atom of calcium contains 20 protons, the nucleus of an average calcium atom must contain 20 neutrons: Mass Number=(Number of Protons)+(Number of Neutrons)Mass Number=(Number of Protons)+(Number of Neutrons) 40=20+Number of Neutrons40=20+Number of Neutrons 40−20=Number of Neutrons40-20=Number of Neutrons 20=Number of Neutrons20=Number of Neutrons An average atom of calcium contains 20 electrons, 20 protons, and 20 neutrons. This matches the characteristics of Element 1.

Which of the following is a mixture? f Glucose g Distilled water h Carbon j Air

Air

Consider any set of three adjacent elements in the same period on the periodic table. For which characteristic is the average for the three elements always equal to the value of the middle element?

Atomic number

An element has an electron configuration of 1s2 2s2 2p6 3s2 Which of these will be in the same group as this element?

B 1s2 2s2 2p6 3s2 3p6 4s2

Which grouping identifies chemical properties?

Combustibility, flammability, reactivity

Chlorine forms a 1- ion. How many electrons does a chloride ion have?

D. 18 ( 1s2, 2s2, 2p6, 3s2, 3p6)

The alkali metals are located in which group of the periodic table?

Group 1

A chemist is examining an unidentified element sample with oxidation states of The element has a shielding effect similar to that of potassium (K). Which statement about the unidentified element is most likely true?

It is a transition metal from the same period as potassium.

Small Periodic Table Section The picture shows a small section of elements from the periodic table. Which element has one more proton than element X?

J 4

A sodium atom has an electron configuration of 1s22s22p63s1. If the sodium atom becomes ionized, its new electron configuration will be the same as which element?

Neon. Explanation: If the sodium is ionised, the outer 3 s 1 electron is lost, so the configuration becomes 1 s 2 2 s 2 2 p 6 , which is the same as neon, N e .

Reactivity increases/decreases rules

Reactivity increases going down the group Reactivity decreases going from left to right across the group

ns2np3ns2np3 Which of these elements is found in a family with the above electron configuration?

Sb

Which of these elements contains four valence electrons? Oxygen g Beryllium h Carbon j Helium

carbon

Cations are formed when neutral atoms lose -

electrons

Iodine-131 is a radioactive isotope with a half-life of 8 days. How many grams of a 64 g sample of iodine-131 will remain at the end of 24 days?

the formula for half life is: #of half life periods= total time/ half life. if it's total time is 24, and it's half life is 8, then the number of periods is 3. since it's starts at 64, you need to divide by 2 after each half life period. after 3 half life periods, there are only 8 grams of iodine- 131. Basically, the mass of the sample is going to split in half every 8 days, so with a time span of 24 days, you would divide 24 by 8 to get that the sample would split in half 3 times. So 64/2=32, 32/2=16, 16/2=8. 8g remaining.

The understanding that the position of an electron in an electron cloud cannot precisely be determined was developed by Werner Heisenberg and is known as the -

uncertainty principle

identify groups of gases and stuff on the periodic table (study)

x

study electron configuration

x

study electronegativity

x

C-12 and C-13 are naturally-occurring isotopes of the element carbon. C-12 occurs 98.89% of the time and C-13 occurs 1.108% of the time. What calculation should be used to determine the atomic mass of this element?

(12×0.9889)+(13×0.01108)

The net charge on an aluminum ion is +3 because there are

13 protons and 10 electrons in the atom

Three elements, X, Y, and Z, have consecutive increasing atomic numbers. If element X is a noble gas, what will be the symbol for the ion of element Z in its compounds?

Z^2+

An Alkali metal with most likely react with..

a halogen

At room temperature, chlorine exists as a gas, bromine exists as a liquid, and iodine exists as a solid. The physical states of these elements indicate that melting point -

increases from top to bottom within group 17 elements

With nn representing the outermost energy level, the electron configuration for that level for elements in Group 14 is -

ns2p2 ?

When compared to sulfur-32, sulfur-34 has more -

number. The mass number is the sum of the number of protons and neutrons within a particular isotope's nucleus: Mass Number=(Number of Protons)+(Number of Neutrons)Mass Number=(Number of Protons)+(Number of Neutrons) Mass Number=(Atomic Number)+(Number of Neutrons)Mass Number=(Atomic Number)+(Number of Neutrons) Sulfur's atomic number is 16. Every atom of sulfur has 16 protons in its nucleus, regardless of its mass number. If every atom of sulfur contains 16 protons, then the only way there can be two different isotopes of sulfur is if one has more neutrons than the other: Number of Neutrons in S-32=Mass Number−Atomic Number=32−16=16Number of Neutrons in S-32=Mass Number-Atomic Number=32-16=16 Number of Neutrons in S-34=Mass Number−Atomic Number=34−16=18Number of Neutrons in S-34=Mass Number-Atomic Number=34-16=18 When compared to sulfur-32, sulfur-34 has more neutrons.