Chemistry

Question 1

Atom

Answer 1

Is the fundamental constituent of matter that retains the properties of an element. It is the smallest unit that has a unique identity. Atoms have distinct properties, composed of of three subatomic particles: protons, neutrons, and electrons.

Question 2

Periodic Table

Answer 2

There are 118 elements of the periodic table. The table is expressed in columns and rows. Starting with hydrogen, which has one proton and increasing proton numbers for each subsequent element.

Question 3

Proton

Answer 3

A positive charged atomic particle.

Question 4

Neutron

Answer 4

An atomic particle with no electric charge.

Question 5

Electron

Answer 5

A negatively charged atomic particle.

Question 6

Parts of an Atom

Answer 6

Structure consisting of a central nucleus containing positively charged protons and neutral neutrons. Surrounding the nucleus are negatively charged electrons. Electrons exist in an electron cloud surrounding the nucleus. Negative electrons are held in shells or energy levels by their attraction to positively charged protons in the nucleus and increase energy with distance from the nucleus. Each atom will always have the same number of protons. Ex: Carbon has 6.

Question 7

Nucleus(atom)

Answer 7

The central part of an atom that contains the protons and neutrons.

Question 8

Isotopes

Answer 8

Atoms of the same element that have different numbers of neutrons but the same number of protons and electrons.

Question 9

Atomic Mass

Answer 9

The sum of the masses of protons and neutrons in one atom of an element. Electrons are so small they do not add to the mass of an atom. Ex: Carbon atom has atomic mass of adding protons and neutrons ( 6 protons +6 neutrons= 12 atomic mass units). Isotope of Carbon can have 6 protons+ 7 neutrons= atomic mass of 13.

Question 10

IONS

Answer 10

A positively or negatively charged atom or molecule. Ex: A sodium (NA) atom is made up of 11 protons and 12 neutrons and 11 electrons surround the nucleus. Because it has a single electron in its valence shell it will lose an electron. A sodium ion that looses its electron becomes a charged sodium ion NA+ because it now has more protons than electrons. Ex: Chlorine has 17 protons and 17 electrons, it is likely to gain an electron and will become a charged chlorine ion Cl- .

Question 10

Atomic Number

Answer 10

The number of protons in the nucleus of an atom gives the atomic number of an atom. Neutral atoms have equal number of protons and electrons. Neutrons do not change the charge because they are not charged particles.

Question 10

Subatomic particles

Answer 10

Have masses and charges related to their identity.

Question 10

Using the Periodic Table I

Answer 10

The periodic table arranges atoms from left to right by increasing atomic number (number of protons). Atoms are neutral, so the number of protons equals the number of electrons. Atomic number is shown as an integer in the periodic table. Atomic mass shown on periodic table is shown in decimal form and determined by percentage of each isotope found in nature for that particular atom.

Question 11

Orbital

Answer 11

An area around the nucleus where an electron can be found. Orbitals accomodate different electron numbers. Ex: S orbital can accomodate 2 electrons at a time. S orbital is closest to the nucleus. Ex: Hydrogen and Helium only have an S orbital that can hold a total of two electrons.

Question 11

Periods

Answer 11

Rows in the periodic table indicate outermost shell of an atom. Numbered periods means different numbered orbitals and can accommodate different electron numbers. Periods represent large electron “highways” with multiple orbital “lanes.” Ex: Period 1 has one S orbital with a maximum of two electrons allowed. Period 2 has two orbitals: s and p. The S orbital can only accommodate two electrons, but P can accomodate 6 electrons. Period 2 can contain a maximum of eight electrons.

Question 11

Using the Periodic Table II

Answer 11

The periodic table puts elements with similar properties in the same vertical columns called Groups. Grouping of atoms by properties means the elements in each group have the same number of valence (bonding ) electrons. The rows in the periodic table are referred to as Periods, and they indicate the outermost shell of an atom. Depending on the number of the period, there are different number of orbitals that accommodate different electron numbers.

Question 12

Valence Electrons

Answer 12

Are in the outermost shell of an atom and participate in chemical reactions (or bonding). Atoms are most stable when they have a full valence shell. They are most likely to move towards stability. Noble gases like helium and neon have full valence shells and are quite stable. They do not react with other atoms because they are so stable, also this makes them inert gases.

Question 13

Valence Electrons II

Answer 13

Atoms gain or lose electrons to achieve full valence shells, forming charged atoms called ions. Gaining electrons typically happens in atoms with valences greater than 4 (usually nonmetals), and losing electrons typically happens in atoms with valences less than 4 (metals). Ex: All the elements in group 15 will gain 3 electrons and become negatively charged ions called (anions).

Question 14

Anions

Answer 14

Negatively charged ions. Ex: nitrogen will have 7 protons and 7 electrons in a neutral atom will gain 3 electrons to fill its valence shell. It will have a -3 charge (7 protons and 10 electrons).

Question 15

Cations

Answer 15

A positively charged ion. Electrons are donated by atoms that prefer to lose electrons, becoming positively charged ions called (cations).

Question 16

Ionic Bonds

Answer 16

The bond between two oppositely charged ions. Bonds that are formed by transfer of electrons between atoms.

Question 17

Ionic compounds

Answer 17

compounds with ionic bonds are soluble in water and conduct electricity. Ex: Sodium loses 1 electron to fill its outer shell, giving it a +1 charge. Chlorine gains an electron to fill its outer shell (taking 1 electron from sodium), giving it a -1 charge. Now positively charged sodium ion is attracted to the positively charged chloride ion.

Question 18

Compound

Answer 18

Substance made of two or more elements.

Question 19

metal

Answer 19

A Substance that is a good conductor of electricity and heat, forms cations by loss of electrons, and yields basic oxides and hydroxides.

Question 20

Non metal

Answer 20

Any element or substance that is not a metal

Question 21

Electron stability

Answer 21

Atoms can share electrons to achieve stability. Ex: Two oxygen (O) atoms have six valence electrons each. If they share two electrons they would both resemble neon in their electron number. It takes two electrons to make one bond, so there are two bonds between O atoms in O2. These are called covalent bonds.

Question 22

Covalent bonds

Answer 22

A chemical bond in which electron pairs are shared between atoms. Ex: Two electrons to make one bond, so there are two bonds between O atoms in O2. Shared bonds are known as covalent bonds.