- basic particle from which all elements are made.
What are atoms made of?
1 - nucleus
- very small center core of an atom, containing protons and neutrons. (plural - nuclei)
1 - atom measurement
- too small to be measured in everyday units of mass (grams or kilograms)
- atomic mass units (amu) used.
1 - element
- pure substance that cannot be broken down into other substances by chemical or physical means
- identified by the number of protons in the nucleus of its atoms.
1 - atomic number
- the number of protons in the nucleus of an element.
1 - isotopes
- atoms with the same number of protons and a different number of neutrons.
1 - mass number
- the sum of protons and neutrons in the nucleus of an atom.
1. - model
- a diagram, a mental picture, a mathematical statement, or an object that helps explain ideas about the natural world
1 - protons
small, positively charged particle in the nucleus
- have no charge, are neutral.
1 - electrons
- move rapidly around the nucleus, have a negative electric charge, indicated by -
2 - atomic mass
- the average mass of all the isotopes of an element
2 - periodic table
- chart of the elements showing the repeating pattern of their properties.
2 - chemical symbol
- one or two letter representation of an element.
2 - period
- a horizontal row of elements in the periodic table.
2 - group
- elements in the same vertical column of the periodic table; also called family.
3 - metal
- class of elements characterized by physical properties including shininess, malleability, ductility, & conductivity.
3 - malleable
- material that can be pounded into shapes.
3 - ductile
- material that can be pulled out into a long wire.
3 - conductivity
- ability of an object to transfer heat or electricity to another object.
3 - reactivity
- the ease and speed with which an element combines, or reacts, with other elements and compounds.
- reactivity decreases from left to right across the periodic table.
3 - corrosion
- the gradual wearing away of a metal element due to a chemical reaction.
3 - alkali metal
- an element in Group 1 of the periodic table; react with other metals by losing one electron - found only in compounds.
3 - alkaline earth metal
- an element in Group 2 of the periodic table; good conductor of electricity, react by losing two electrons.
3 - transition metal
- one of the elements in Groups 3 through 12 of the periodic table; iron, copper, nickel, silver & gold. Metals are hard & shiny, good conductors of electricity, form colorful compounds.
3 - particle accelerator
- a machine that moves atomic nuclei at higher and higher speeds until they crash into one another, sometimes forming heavier elements
3 - alloy
-a mixture of two or more elements, one of which is a metal.
3 - lanthanides
- top row of elements placed below the main part of the periodic table.
- are soft, malleable, shiny metals with high conductivity
3 - actinides
- second row of elements placed below the main part of the periodic table.
-first 4 elements occur naturally on Earth; elements heavier than uranium are created artificially.
4 - nonmetal
- element lacking most of the properties of a metal.
- poor conductor of electricity and heat
- reactive with other elements
- solid nonmetals are dull and brittle
4 - halogens
- elements found in Group 17 of the periodic table
- means "salt forming"
- all but astatine are nonmetals
- most reactive nonmetals
4 - noble gases
- elements in Group 18
- do not ordinarily form compounds because atoms do not usually gain, lose, or share electrons.
- usually unreactive.
4 - metalloids
- an element that have some characteristics of both metals and nonmetal
- most useful property is their varying ability to conduct electricity.
4 - semiconductors
- substances that can conduct electricity under some but not all conditions (heat, light, temperature)
5 - plasma
- gas-like state of matter consisting of a mixture of free electrons and atoms that are stripped of their electrons.
5 - nuclear fusion
- process in which two atomic nuclei combine to form a larger nucleus, forming a heavier element and releasing huge amounts of energy.
5 - nebula
- cloudlike region of gases left over in the remains of a shrinking, sun-sized star
5 - supernova
- explosion of a massive star.
How can an element be identified?
An element is identified by the number of protons in the nucleus of its atoms
Who is Mendeleev?
Russian scientist who discoverd a set of patterns that applied to all the elements.
What does each square on the perodic table include?
How is the modern perodic table organized
The modern day perodic table is organized by the atomic number.
How are elements arranged in groups on the periodic table?
-There are 18 groups also called families on the periodic table
-They are vertical columns
Which group contains the most elements?
How can an element be predicted on the periodic table?
by its atomic number
How are elements in the same row alike?
their properties change by the same pattern- reactive to unreactive to VERY unreactive
What are some physical & chemical properties of metals?
shininess, malleable, conductivity, reactivity & ductile
What are the two common alkaline earth metals?
Magnesium & Calcium
What are transition metals?
the elements in groups 3-12; hard, shiney, good conductors that form colorful compounds (gold, silver, copper)
How can you know an element's reactivity using the periodic table?
On left- most reactive & on right- least reactive
Where are the most reactive elements found?
How are elements that follow uranium on the periodic table made?
artificially in a lab
What are some physical and chemical properties on nonmetals?
poor conductors; solids are dull, brittle and crumble. 16 are gases
Describe how electrical wire is made with metals and non metals.
Inside- copper that is shaped becuse it is malleable and ductile. It has good conductivity to carry electricity. Outside is non-metal to insulate the electricity.
What is the most useful property of metalloids?
What are some elements that are part of the halogen family?
"salt-forming" chlorine, flourine, iodine
What do scientist use to make most synthetic elements?
What occurs during nuclear fusion in stars?
heavier elements are made by combining smaller nuclei into larger nuclei
What provides enough energy for nuclear fusion reactions?
high temperature and pressure
What is the sun made mostly of?
- molecule consisting of two atoms. ex- Nitrogen
Why would it be difficult to determine the properities of a newly discoverd synthetic element?