Chapter 4: Atoms and Elements

Draw the Lewis Symbol for each of the following elements: A) Chlorine B) Selenium C) Potassium

.. A) :Cl: <- . .. B) .Se: <- . C) K <- .

Consider the following pairs of atoms in which X represents the chemical symbol of the element: A) 15/8X 15/7X B) 12/6X 14/6X C) 15/7X 16/8X 1) Which of the pairs are isotopes of the same element? 2) In which of the pairs do both atoms have eight neutrons?

1) B 2) C

At atom has 14 protons and 20 neutrons. A) What is its atomic number? 1) 6 2) 14 3) 34 B) What is its mass number? 1) 14 2) 16 3) 34 C) What is the element) 1) Si 2) Ca 3) Se

A) 14 B) 34 C) Si

Write the atomic symbol for the following atoms: A) 8 protons 8 neutrons 8 electrons B) 17 protons 20 neutrons 17 electrons C) 47 protons 60 neutrons 47 electrons

A) 16/8 O B) 37/17 Cl C) 107/47 Ag

Using the periodic table, write the group number and the number of valence electrons for each of the following elements: A) strontium B) argon C) silicon

A) 2 B) 8 C) 4

An atom of lead (Pb) has a mass number of 207. A) How many protons are in the nucleus? B) How many neutrons are in the nucleus? C) How many lectrons are in the atom?

A) 82 B) (207-82)= 125 C) 82

Select the correct number of protons in each atom: A) fluorine atom 1) 9 protons 2) 17 protons 3) 10 protons B) Potassium 1) 15 protons 2) 39 protons 3) 19 protons C) barium atom 1) 137 protons 2) 56 protons 3) 81 protons

A) 9 protons B) 19 protons C) 56 protons

Group 7A (17), Period 4 A) Br B) Cl C) Mn

A) Br

Identify the element in each pair that has the more metallic character A) K or Li B) S or Si C) potassium or bromine

A) K B) Si C) K

Identify the larger atom in each pair: A) K or Li B) S or Si C) potassium or bromine

A) K B) Si C) K

Given the following elements, answer the questions : Li, N, F A) Which is the largest atom? B) Which has the highest ionization energy? C) Which belongs to Group 5A (15)? D) Which has the most metallic character?

A) Li B) F C) N D) Li

Identify the element in each pair that has the higher ionization energy A) K or Li B) S or Si C) potassium or bromine

A) Li B) S C) Br

Identify the form of electromagnetic radiation in each pair that has the greater energy: A) pillow light or blue light B) ultraviolet light or infrared light C) x-rays or microwaves

A) blue B) UV C) x-ray

Which of the following subatomic particles fits each- proton, neutron, electron: A) found outside the nucleus B) has a positive charge C) has mass but no charge

A) electron B) protons C) neutron

Identify each of the following elements as a metal, nonmetal or metalloid: A) sodium B) bromine C) boron D) manganese E) carbon

A) metal B) nonmetal C) metalloid D) metal E) nonmetal

Group 5A (15), Period 2 A) phosphorous B) nitrogen C) arsenic

B) nitrogen

Group 6B (6), Period 4 A) copper B) selenium C) chromium

C) chromium

Group 2A (2), Period 3 A) beryllium B) boron C) magnesium

C) magnesium

Representative elements

Group 1A (1), called the alkali metals: Li, Na, K, Rb, Cs and Fr group 2A (2), called the alkaline earth metals: Be, Mg, Ca, Sr, Ba and Ra Groups 3A (13), 4A (14), 5A (15) and 6A (16) Group 7A (17), called the halogens: F, Cl, Br, I, At and Ts Group 8A (18), called the noble gases: He, Ne, Ar, Kr, Xe, Rn, and Og

There are 3 naturally occurring isotopes of potassium, K-39, K-40 and K-41. If the atomic mass for potassium on the period table is 39.10, which isotope potassium is most abundant?

K-39

At atom consists of

a nucleus that contains protons (+) and neutrons (0) electrons (-) in a large, empty space around the nucleus

Metallic character

an element with metallic character is one that loses valance electrons easily is higher in the elements (metals) on the left side of the period table is lower in the elements (nonmetals) on the right side of the periodic table, which do not lose electrons easily metallic character of the representative elements increases going down a group and decrease going from left to right across a period

Isotopes

are atoms of the same element that have different mass numbers have the same number of protons, but different numbers of neutrons

The periodic table

arranged elements by increasing atomic mass arranged elements into groups with similar properties

Metalloids

elements along the zigzag line include B, Si, Ge, As, Sb, Te, Po, At and Ts exhibit some properties typical of metals and some typical of nonmetals are better conductors of heat and electricity than nonmetals, but not as good as metals are semiconductors because they can be modified to function as conductors or insulators

On the periodic table,

elements are arranged according to similar properties in vertical columns called groups periods are horizontal rows of elements, counted from top to bottom of the table as periods 1-7 period 1 contains two elements: H and He Periods 2 and 3 each contain eight elements: Period 2- Li, Be, B, B, N, O, F, Ne Period 3- Na, Mg, Al, Si, P, S, Cl, Ar

Subatomic particles

experiments with electricity showed that atoms were composed of tiny particles called subatomic particles, including protons, neutrons and electrons it was shown that some subatomic particles in an atom have charge

Group numbers and valence electrons

for representative elements in groups 1A (1) to 8A (18), chemical properties are mostly due to the number of valence electrons valence electrons are the electrons in the outermost energy level the group number gives the number of valence electrons for the representative elements

Group numbers

identify vertical columns of the periodic table are written in 2 ways: the letter A is used for the representative elements 1A to 8A and the letter B for the transition elements the numbers 1 to 18 are used for the columns from left to right

Nonmetals

include elements such as hydrogen (H), carbon (C), nitrogen (N), oxygen (O), chlorine (Cl) and sulfur (S) are not especially shiny, ductile or malleable are are often poor conductors of heat and electricity, brittle typically have low melting points and low densities

Lewis symbols

is a convenient way to represent the valence electrons of an element dots are places on the sides, top, or bottom of the symbol for the element for example, three dots are places around the symbol Al to represent the three valence electrons

The atomic number

is a whole number specific for each element is the same for all atoms of that element is equal to the number of protons in an atom appears above the symbol of an element in the periodic table

Atomic size

is determined by the distance of the valence electrons from the nucleus of the atom increases for representative elements going from top to bottom of the periodic table decreases going from left to right across a period as a result of the increased number of protons in the nucleus for representative elements, the atomic size increases going down a group bit decreases going from left to right across a period

An atom of any element,

is electrically neutral; it has a net charge of zero has an equal number of protons and electrons a neutral atom of calcium, atomic number 20, contains 20 protons and 20 electrons. it has zero net charge

Ionization energy

is the energy required to remove one of the outermost electrons ionization energy for the representative elements decrease going down a group and increase going across a period from left to right

The atomic mass of an element is

listed below the symbol of each element on the period table calculated based on the weighted average of all naturally occurring isotopes based on its comparison to the mass of carbon-12 not the same as the mass number

Metals, Nonmetals and metalloids

metals are located to the left nonmetals are located to the right metalloids are located along the heavy zigzag line between the metal and nonmetals

Metals

most are shiny solids, such as copper (Cu), gold (Au) and silver (Ag) ductile, meaning they can be shaped into wires malleable, meaning they can be hammered into a flat sheet good conductors of electricity melted at much higher temps than nonmetals solids at room temp, except for mercury (Hg)

Chemical Symbols

one- or two-letter abbreviations for an elements name when chemical symbols contain two letters, the second letter is NOT capitalized Co is the chemical symbol for cobalt CO specifies there are two elements present, carbon and oxygen

Periodic properties

periodic properties (such as atomic size, ionization energy and metallic character) increase or decrease across a period, and then the trend is repeated in each successive period

The atomic symbol

represents a particular isotope of an element gives the mass number in the upper left corner and the atomic number in the lower left corner

The mass number

represents the number of particles in the nucleus is equal to the number of protons + the number of neutrons does not appear in the periodic table because it applies to single atoms only

The electromagnetic spectrum

shows the arrangement of wavelengths of electromagnetic radiation, with the visible range from 700 to 400 nm

Atom

the smallest particle of an element that retains the characteristics of that element all of the elements listed on the periodic table are made up of atoms

Calculating atomic mass

use an experimental percent abundance of each isotope of the element multiply the percent abundance by the atomic mass of that isotope sum the total mass of each isotope

Electromagnetic radiation

we experience electromagnetic radiation in different forms when we listen to a radio, use a microwave oven, see colors in a rainbow or have an x-ray taken all types of electromagnetic radiation, including light, consist of particles that move as waves of energy the distance between the peaks of waves is called the wavelength high-energy radiation has shorter wavelengths low-energy radiation has longer wavelengths