atoms, elements and compounds

Question 1

what is the relative mass of protons and neutrons

Answer 1

proton- 1

neutron - 1

Question 2

what is the relative mass of electrons

Answer 2

1/ 1840

Question 3

what is the atomic number or proton number

Answer 3

The atomic number (or proton number) is the number of protons in the nucleus of an atom.

Question 4

what is the nucleon or mass number

Answer 4

Nucleon number (or mass number) is the total number of protons and neutrons in the nucleus of an atom

Question 5

in the periodic table, what position is the mass number and atomic number on

Answer 5

mass number= top
atomic number = bottom

Think MASS = MASSIVE, as the mass number is always the bigger of the two numbers, the other smaller one is thus the atomic / proton number.

Question 6

what is the mass number

Answer 6

number of nucleons in a nucleus

Question 7

how are elements arranged in the periodic table

Answer 7

Elements are arranged on the Periodic table in order of increasing atomic number where each element has one proton more than the element preceding it

Question 8

what are groups and periouds

Answer 8

ertical columns called Groups numbered I – VIII and in rows called Periods

Question 9

what simmilar characteristics do elements in the same group share

Answer 9

Elements in the same group have the same amount of electrons in their outer shell, which gives them similar chemical properties

Question 10

what are isotopes

Answer 10

Isotopes are atoms of the same element that contain the same number of protons and electrons but a different number of neutrons.

Question 11

what are the two categories of isotopes

Answer 11

radioactive and non-radioactive

Question 12

what are radiocative isotopes

Answer 12

Radioactive isotopes (radioisotopes) are unstable due to the imbalance of neutrons and protons, which causes the nucleus to decay over time through nuclear fission and emit radiation.

Question 13

what are the medical uses of radioactive isotopes

Answer 13

1. treat cancer

2. sterelization

Question 14

what are the industral uses of radioactive isotopes

Answer 14

1. radioactive dating
2. detect leaks
3. used as nuclear in power plants

Question 15

why do isotopes share properties

Answer 15

because they have the same number of electrons in their outer shells and this is what determines an atom’s chemistry
The difference between isotopes is the neutrons which are neutral particles within the nucleus and add mass only

Question 16

how is energy related to the nucleus

Answer 16

The further away from the nucleus then the more energy a shell has.

Question 17

what is the valance shell

Answer 17

The outermost shell of an atom is called the valence shell and an atom is much more stable if it can manage to completely fill this shell with electrons

Question 18

what is an element

Answer 18

A substance made of atoms that all contain the same number of protons (one type of atom) and cannot be split into anything simpler

Question 19

what is a compound

Answer 19

A pure substance made up of two or more elements chemically combined

Question 20

how can compounds be seperated

Answer 20

Compounds cannot be separated into their elements by physical means

Question 21

what is a mixture

Answer 21

A combination of two or more substances (elements and/or compounds) that are not chemically combined

Question 22

how can mixtures be separated

Answer 22

Mixtures can be separated by physical methods such as filtration or evaporation

Question 23

name 4 properties of metals

Answer 23

1. Conduct heat and electricity
2. Are malleable and ductile (can be hammered and pulled into different shapes)
3. Tend to be lustrous (shiny)
4. Have high density and usually have high melting points

Question 24

name four properties of nonmetals

Answer 24

1. Do not conduct heat and electricity
2. Are brittle and delicate when solid and easily break up
3. Tend to be dull and nonreflective
4. Have low density and low melting points (many are gases at room temperature)

Question 25

what is an alloy

Answer 25

Alloys are mixtures of metals, where the metals are mixed together but are not chemically combined

Question 26

why are alloys harder than pure element

Answer 26

Alloys contain atoms of different sizes, which distorts the regular arrangements of atoms
This makes it more difficult for the layers to slide over each other, so they are usually much harder than the pure metal

Question 27

what is brass

Answer 27

Brass is a common example of an alloy which contains 70% copper and 30% zinc

Question 28

what is an ion

Answer 28

An ion is an electrically charged atom or group of atoms formed by the loss or gain of electrons

Question 29

what is the ionisation of metals

Answer 29

all metals lose electrons to other atoms to become positively charged ions

Question 30

what is the ionisation of non metals

Answer 30

all non-metals gain electrons from other atoms to become negatively charged ions

Question 31

how are covalent compounds formed

Answer 31

Covalent compounds are formed when electrons are shared between atoms

Question 32

what elements form covalent compounds

Answer 32

Only non-metal elements participate in covalent bonding

Question 33

name 3 characteristics of compounds

Answer 33

1. Have high melting and boiling points so ionic compounds are usually solid at room temperature
2. Not volatile so they don’t evaporate easily
3. Conduct electricity in molten state or in solution as they have ions that can move and carry a charge

Question 34

name 3 characteristics of covalent compounds

Answer 34

1. Have low melting and boiling points so covalent compounds are usually liquids or gases at room temperature
2. Usually volatile
3. Cannot conduct electricity as all electrons are involved in bonding so there are no free electrons or ions to carry the charge

Question 35

why do ionic compounds have high melting and boiling points

Answer 35

because the oppositely charged ions in the lattice structure are attracted to each other by strong electrostatic forces which hold them firmly in place
Large amounts of energy are needed to overcome these forces so the m.p. and b.p. are high

Question 36

why do simple covalent substunces have low meltig and boiling points

Answer 36

Simple covalent substances, have very strong covalent bonds between the atoms in each molecule, but much weaker intermolecular forces between individual molecules
When one of these substances melts or boils, it is these weak intermolecular forces that break, not the strong covalent bonds
Less energy is needed to break the molecules apart, so they have lower m.p. and b.p. than ionic compounds

Question 37

what is diamond and graphite

Answer 37

Diamond and graphite are allotropes of carbon

Question 38

what are the three characteristics of diamond

Answer 38

1. Does not conduct electricity
2. Has a very high melting point
3. Is extremely hard and dense

Question 39

what is diamonds used for

Answer 39

Diamond is used in jewellery and as cutting tools

Question 40

what are the 3 characteristics of graphite

Answer 40

1. Conducts electricity
2. Has a very high melting point
3. Is soft and slippery, less dense than diamond

Question 41

what is graphite used for

Answer 41

Graphite is used in pencils and as an industrial lubricant, in engines and in locks