Structure Of The Atom

Question 1

what is a compound

Answer 1

compounds are composed of two or more elements chemically joined in a fixed ratio

Question 2

what is an atom

Answer 2

atoms are the smallest parts of an element that can take part in a chemical reaction

Question 3

what is in the nucleus

Answer 3

• protons (positive)
• neutrons (no charge - neutral)
• extremely tightly packed together
• nucleus has overall positive charge

Question 4

what are electrons

Answer 4

• negative charge
• orbit very fast in the region of space around the nucleus
• attraction between protons and electrons help maintain the electrons in the electron cloud

Question 5

what is the mass number

Answer 5

number of protons + number of neutrons

Question 6

what is the atomic number

Answer 6

• number of protons

- number of electrons

Question 7

what is an isotope

Answer 7

• an element that contains a different number of neutrons (diff mass number)
• same chemical properties (same element)

Question 8

what is important about electrons

Answer 8

• chemical properties of an atom are controlled by electrons

- the nucleus does not affect and is not changed in chemical reactions

Question 9

how can you represent the electron configuration

Answer 9

• dot / cross diagram or energy level diagram

- shows all electrons (in energy shells)

Question 10

what can the periods tell us

Answer 10

number of energy levels

Question 11

what can the groups determine

Answer 11

number of valence electrons

Question 12

what does it mean if elements are in the same group

Answer 12

• similar chemical properties

- controlled by how many valence electrons an atom has

Question 13

what is a noble gas

Answer 13

an element with 8 electrons in their outermost shell

Question 14

what happens when elements react

Answer 14

• atoms involved collide, causing the outermost electrons to interact
• when they react they try get the same electron configuration as the nearest noble gas

Question 15

what is an electron dot diagram

Answer 15

a way to show the outermost electron energy shell

Question 16

why do elements react with one another

Answer 16

• to become more stable and have less energy

Question 17

what happens when elements bond

Answer 17

• the valence electrons interact and they cause atoms to join together and a new chemical bond is formed

Question 18

what is an ion

Answer 18

an atom or group of atoms with an electrical charge

Question 19

what is the overall charge of an atom

Answer 19

• generally the protons (positive and electrons (negative) balance eachother out

Question 20

what happens if an atom looses an electron

Answer 20

• the atom becomes unbalanced

- creating an overall positive or negative charge

Question 21

what is a cation

Answer 21

positive ion, loses electrons (usually metal)

Question 22

what is an anion

Answer 22

a negative ion, gains electrons

Question 23

what is a poly atomic ion

Answer 23

a group of ions that have a charge

Question 24

what is ionic bonding

Answer 24

• occurs when a nonmetal reacts with a metal

- the electrostatic attraction between the positive metal ions and the negative nonmetal ions

Question 25

what are the properties of ionic bonding

Answer 25

• non conductor when solid
• conductor when liquid
• brittle
• high melting point

Question 26

what is metallic bonding

Answer 26

• metal atoms lose valence electrons (positive ions) valence electrons become delocalised and mobile
• the electrostatic attraction between the positive metal ions and the valence electrons

Question 27

properties of metallic bonding

Answer 27

• conduct electricity
• conduct heat
• ductile / malleable
• high melting point
• shiny

Question 28

what is covalent bonding

Answer 28

• occurs when nonmetal atoms come together, electrons are shared (stable electron configuration)
• electrostatic attraction between the negative shared electrons and the positive nuclei of the adjacent atoms

Question 29

what is covalent molecular

Answer 29

when covalent bonding is restricted to just a few atoms

Question 30

what is a covalent network

Answer 30

a covalent bond that extends through the substance (graphite, silicon)

Question 31

properties of covalent bonding

Answer 31

• very low melting point
• soft / waxy
• nonconductor of electricity

Question 32

what is the formula of an ionic substance

Answer 32

provides the ratio of ions present not the actual number of ions present

Question 33

what is an element

Answer 33

elements are the simplest substances, they cannot be broken down into simpler substances by chemical means

Question 34

what is the formula of a metallic substance

Answer 34

name = name of element 
formula = single symbol that does not indicate the number of atoms present

Question 35

what is the formula of a covalent molecular substance

Answer 35

the name indicates the number and type of atoms present in a molecule of that substance

Question 36

how do you write a covalent molecular substance

Answer 36

• element closer to left goes first
• element closer to right goes second (end changes to ‘ide’)
• use prefixes to determine the number of each atom
• if there is one of both atoms don’t use mono
• molecules composed of one element get the name of the element

Question 37

what are the prefixes used in covalent molecular formula writing

Answer 37

mono - 1 
di - 2 
tri - 3
tetra - 4
pent - 5
hex - 6
hept - 7 
oct - 8
non - 9
dec - 10

Question 38

how do you write an ionic substance

Answer 38

• positive ion first
• negative ion second
• number of ions is adjusted so that positive charge = negative charge