Science Chapter 3 Flashcard

Atoms are made of?
smaller particles called protons, neutrons, and electrons.
Nucleus
the very small center core of an atom. Made up of a group of smaller particles called protons and neutrons.
Protons
have a positive charge
Neutrons
have no charge
Electrons
move rapidly around the nucleus and have a negative electric charge
An element can be identified by?
the number of protons in the nucleus
atomic number
the number of protons in its nucleus
isotopes
atoms with the same number of protons and a different number of neutrons
mass number
the sum of the protons and neutron in the nucleus of an atom
Why do scientists create models for atoms?
atoms are to small
model
a diagram, a mental picture, a mathematical statement, or an object that helps explain ideas about the natural world
atomic mass
the average mass of all the isotopes of that element
What did Mendeleev notice about patterns?
he noticed that a pattern of properties appeared when he arranged the elements in order of increasing atomic mass
periodic table
a chart of the elements showing the repeating pattern of their properties
chemical symbol
a one or two letter representation of an element

Each square in the periodic table includes?

*4 

  1. the element’s atomic number
  2. chemical symbol
  3. name
  4. atomic mass

The properties of an element can be predicted, how?
from the location in the periodic table
periods
the table is arranged in horizontal rows
group
the elements in a column. also, know as families
The physical properties of metals

  • shininess
  • malleability
  • ductility
  • conductivity

Malleable
one that can be hammered or rolled into flat sheets and other shapes
conductivity
the ability of an object to transfer heat or electricity to another object
reactivity
the ease and speed with which an element combines, or reacts, with other elements and compounds
corrosion
the destruction of a metal through this process
alkali metals
the metals in Group 1, from lithium to francium
How does the reactivity of metal decrease?
you move from left to right across the periodic table
alkaline earth metals

Group 2 of the periodic table

;

transition metals

  • the elements in groups 3 through 12
  • hard and shiny
  • good conductors of electricity

alloy
a mixture of a metal with at least one other element, usually another metal.
Particle Accelerators

  • Elements that follow uranium are made—or synthesized—when nuclear particles are forced to crash into one another
  • move atomic nuclei faster and faster until they have reached high speeds and crash into each other

 

nonmetal
an element that lacks most of the properties of a metal
Most nonmetals are?

  • poor conductors of electricity and heat and reactive with other elements
  • solid nonmetals are dull and brittle

Diatomic Molecule
consists of two atoms
halogens

 

  • an element found in Group 17 of the periodic table
  • which means salt forming
  • very reactive

 

Noble Gases
the elements in Group 18
Metalloids
have some characteristics of both metals and nonmetals
The most useful property of the metalloids
their varying ability to conduct electricity
Semiconductors
substances that can conduct electricity under some conditions but not under other conditions
Plasma
state of matter consists of a gas-like mixture of free electrons and atoms stripped of electrons
Nuclear Fusion

  • a process in which two atomic nuclei combine to from a larger nucleus, releasing huge amounts of energy in the process
  • combines smaller nuclei into larger nuclei, creating heavier elements

Nebula

  • cloudlike region of gases
  • a star like the sun shrinks, and its elements spread into space

supernova

  • a huge explosion that breaks apart a massive star, producing temperatures up to 1 billion degrees Celsius
  • provides enough energy for the nuclear fusion reactions that create the heaviest elements

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